"Rehman, a dreaded terrorist, exported by Pakistan based ISI, is wanted in a series of bombings carried out all over India along with his absconding associates," Special Commissioner (Special Cell) S N Shrivastava told reporters here today, adding it was a "major catch".

He was arrested outside Ajmer Railway Station early yesterday morning when he alighted from a train which came from Bandra, Mumbai.

His other three associates identified as Mohammad Mahruf (21), Mohammad Waqar Azhar alias Haneef (21), both residents of Jaipur, and Shaquib Ansari alias Khalid (25) of Jodhpur were arrested at his instance in the wee hours today from their residences with the help of Rajasthan police.

A youth, whose identity police did not reveal, was picked up for questioning from Shaheen Bagh area from Jamia Nagar for questioning as he was in touch with the three arrested from Jaipur and Jodhpur.

"We have recovered huge amount of explosive materials, detonators, electronic circuits/timers from the residence of these three people from Jaipur and Jodhpur. With this, a spectacular terrorist strike has been averted," said Shrivastava.

Asked whether the terrorists had plans to target BJP's Prime Ministerial candidate Narendra Modi, Shirvastava said, "Present level of investigation doesn't point towards it."

On whether the terrorists were planning attack on any politician or rally during Lok Sabha elections, he said, "Any important event including elections can be targeted but we are at a very preliminary stage of investigation and I would not like to speculate as if now."

Cases have been registered under Explosive Substances Act at Jaipur and Jodhpur in connection with the recoveries made from the terrorists.

25-year-old Rehman has disclosed that the purpose of his visit to Ajmer was to coordinate and oversee the preparations being carried out by the three terrorists of the Rajasthan module for carrying out a spectacular terror strike, said Shrivastava.

An expert in IED and other explosives, Rehman was brought to Delhi and produced in a Special Court which remanded him in 10-day police custody. His detailed interrogation is under way, police said.

Mahruf and Waqar are engineering students in Jaipur while Ansari is running a computer DTP and design printing business, said Shrivastava.

Trained in terror camps in Pakistan, Waqas was allegedly involved in the Jama Masjid attacks on September 19, 2010, the Sheetla Ghat, Varanasi blasts carried out on December 7, 2010, the blasts carried out at Opera House and Zaveri Bazar in Mumbai on July 12, 2011.

The next terrorist strike carried out by Waqas was the Pune serial blasts of August 1, 2012. He was also involved in the Hyderabad serial blasts carried out on February 21, 2013.

Some activists and locals staged a protest outside Jamia Nagar police station today over what they termed as "illegal arrest" of two youths from the area at about 7 AM today allegedly by Delhi Police Special Cell.

Police, however, said that they have detained one youth for questioning.

"The two youths, basically from Bihar, who were residing at house number 101-A in Hari Khothi Lane, Abul Fazal Enclave, were taken into custody by police early morning. One of the two is a Mechanical Engineering final year student in a college in Jaipur," a local claimed.

Although police recovered only mobile phones and some other itmes from Waqas at the time of his arrest, pen drives, explosives, timers, circuits, watches and other material were seized from Ansari, Maruf and Waqar.

From Ansari, police recovered a laptop, mobile phone, detonators, circuit, timers, explosives while one laptop, mobile phones, pen drive and other material were seized from Maruf.

"The largest seizure was made from Waqar. We seized mobile phones, pen drive, and other incriminating documents/books from a black bag. We also found 10 watches, two detonators, two small plastic bottles ball bearing, two complete circuits, batteries, nails, some silver colour explosive material.

"Two bottles containing Magnesium Sulphate, castor seeds, four transit circuit, 10 circuit plates, soldering rods, sodium chloride among others," said an official associated with the investigation.

According to investigators, Waqas had stayed in Mumbai for some days before boarding a train to Ajmer.

The terrorists were either waiting for an opportune time to strike or instructions from the higher ups, the official said.

The Special Cell had been following the clues which had come out from the interrogations of Ahmad Siddhibappa Zarar alias Yasin Bhatkal, Indian Mujahideen co-founder and one of India's most wanted terrorists and Asadullah Akhtar alias Haddi.

It was also following leads from two dreaded terrorists and associates of Waqas, who had been arrested in August last year from Indo-Nepal for their alleged involvement in a spate of terrorist bombings, police said.

From Pakistan, Waqas had reached Kathmandu along with Asadullah Akhtar alias Haddi (arrested with Yasin Bhatkal) in September 2010 and was received by Tehseen Akhtar alias Monu, the current Chief of Indian Mujahideen after the arrest of Bhatkal.

"Although, Waqas and Haddi came from the same flight they were not known to each other and it was Akhtar who introduced them," said Shrivastava.

From Nepal, Waqas came to Darbhanga in Bihar where he met Yaseen Bhatkal and other members of the Bihar module of IM. This module then carried out the Jama Masjid attacks on September 19, 2010. After successfully executing the Jama Masjid terror strikes, Waqas returned to Bihar, police said. 

In Bihar, after carrying out a comprehensive review of the Jama Masjid attacks wherein the IED prepared by this module did not have the desired impact, Waqas informed Yasin Bhatkal about his expertise in making Hydrogen Peroxide based IEDs.

"This later led to the Sheetla Ghat, Varanasi blasts carried out on December 7, 2010. While fabricating the IEDs for this strike, Waqas suffered an injury while connecting the detonator and the timer as the detonator went off. It injured two fingers of Waqas's left hand.

"After the Varanasi bombings, as per the directions of Yasin Bhatkal, Waqas shifted to Mumbai where he stayed in a rented accommodation at Habib Apartment, Byculla. In June 2011, Waqas, Yasin Bhatkal, Asadullah Akhtar alias Haddi and Tehseen Akhtar alias Monu started preparations for the Mumbai serial blasts. After preparing the IEDs, blasts were carried out at Opera House and Zaveri Bazar," said Shrivastava.

The next terrorist strike carried out by Waqas was the Pune serial blasts of August 1, 2012. Here, he partnered with Asadullah Akhtar alias Haddi and the Maharashtra module of IM consisting of Asad, Imran, Irfan, Feroze and Sayed Maqbool (all since arrested by the Special Cell).

After carrying out the Pune blasts, which did not yield the desired results, Waqas and Asadullah Akhtar alias Haddi left for Mangalore and settled in a safehouse.

In Mangalore, Waqas received instructions from Riyaz Bhatkal to prepare for carrying out bomb blasts in Hyderabad. Early February 2013, Waqas and Asadullah Akhtar alias Haddi shifted to Hyderabad where Tehseen Akhtar also joined them.

The Hyderabad serial blasts were successfully executed by these three terrorists on February 21, 2013. After carrying out this strike, Waqas returned to Mangalore and stayed there for some time. When the news of the arrest of Yasin Bhatkal and Asadullah Akhtar by the Indian security agencies broke out, Riyaz directed Waqas to leave the Mangalore hideout immediately.

Waqas moved to Munnar in Kerala and took a rented accommodation there. Tehseen Akhtar also visited him there for a short period. After staying in Munnar, Waqas kept roaming in Orissa, West Bengal, Maharashtra while keeping in touch with Riyaz Bhatkal and Tehseen Akhtar. On the directions of Akhtar to come to Ajmer for an assignment, he came to Ajmer from where he was arrested. 

The Rajasthan module is not new for investigators as the Special Cell had been working on it after the existence of such a module was disclosed by Yasin Bhatkal and Haddi during their interrogations.

However, the interrogations of these two accused could not yield anything specific regarding the identity of the members of this module apart from the stated fact that it was developed by absconding terrorist Tehsin Akhtar directly under the command of Riyaz and Iqbal Bhatkal.

According to police sources, during his interrogation Bhatkal had said, "ladke bade achche hain" (the boys are good), while talking about the Rajasthan module.

Ever since then, the Special Cell had been trying to identify the suspects based in Rajasthan who could be connected to Tehsin Akhtar. After intensive efforts spread over a period of over three months, certain suspects were identified their movements and activities were watched, police said.

"The arrest of Waqas and his subsequent interrogation provided specific identities of the members of this module. Arrested Mohd Mahruf is pursuing engineering degree from VIT, Jagatpura, Jaipur, Mohd Waqar Azhar is also pursuing engineering degree from Global Institute of Technology, Sitapura, Jaipur and Shaquib Ansari is running a computer DTP and design printing business," said Shrivastava.

They are being brought to Delhi and their detailed interrogations will reveal the plans of this module and also help in establishing the identities of their other member associates, financers, sympathisers etc, police said.