With intelligence inputs warning of a possible terror strike, unprecedented security measures were put in place across the country for Republic Day celebrations that passed off peacefully today.

However, a few incidents including an encounter in South Kashmir where an unidentified militant was killed, and a bomb scare sparked by an unclaimed bag at a Pathankot railway station set off alarm.

The national capital was brought under an unprecedented ground-to-air security cover with thousands of armed personnel keeping a tight vigil for the 67th Republic Day celebrations where French President Francois Hollande was the Chief Guest.

The area around Central Delhi was turned into a virtual fortress in view of intelligence inputs that terror groups may target some important installations in the city.

The measures were adopted in the aftermath of the terror attack on the Pathankot airbase.

Ahead of the Republic Day celebrations, central security agencies and NIA busted a module by arresting 14 militants linked to terror group ISIS, who, officials claimed, had planned to carry out strikes at important installations.

Commandos with light machine guns were deployed at 10 strategic locations and anti-aircraft guns remained positioned at two vantage points in the capital.

The entire region of Central and New Delhi had nearly 50,000 security personnel drawn from Delhi Police and central security forces guarding every nook and corner.

Special arrangements were made at the historic Rajpath where India's military might was on display.

Hollande was seated along with President Pranab Mukherjee and host of VVIPs including Vice President Hamid Ansari and Prime Minister Narendra Modi.

The VVIP enclosure was put under a multi-layer security ring with Presidential Guards and officials of SPG and NSG guarding the two inner-most orbits and Delhi Police entrusted with guarding the outermost circle, said a senior official.

Senior officials said snipers have been put atop 45 buildings overlooking Rajpath besides providing a similar cover along all the buildings along the parade route.

Gunners have been given clear instructions to bring down any aerial object flying without permission. A 'NOTAM' (Notice to Airmen) has been declared from 10.35 AM to 12.15 PM during which no flight will land or take off at the Indira Gandhi International Airport.  

A special control room has been monitoring as many as 15,000 CCTV cameras installed across Central and New Delhi, with 200 high-tech digital cameras installed in the parade route, an official said.

As many as 1,000 traffic officials have been issued revolvers so that they can deal with any untoward incident amid heavy security arrangements across the city involving around 25,000 police officials.

In Punjab, additional personnel were posted at bus stands, railway stations and government buildings. Similar arrangements were in place in Haryana and the Union Territory of Chandigarh.

However, in Pathankot, an unclaimed bag at a railway station sparked a security scare in the district where police and agencies are on high alert following the terror strike at air base early this month, in which seven security personnel were killed.

People were swiftly evacuated from the area and rail traffic had also been halted or diverted for the time being on the route, police said.Bomb disposal and dog squads were summoned to identify the contents of the bag, which has been covered by sand bags, they said.

"A bag has been found at the railway station. We are taking all precautions. We are verifying its content," R K Bakshi, Pathankot SSP, said.

He said that security agencies were taking no chances and as a precautionary measure, they had cleared the area.

In South Kashmir's Anantnag district, an unidentified militant was killed in a gunbattle which broke out around 4 AM. In Jammu and Kashmir, security had been stepped up across the Valley to thwart any plan by militants to disrupt the celebrations.

Meanwhile, Uttarakhand Police detected a CCTV grab of a terror suspect seen in the company of seven to eight others who could be his associates, prompting the authorities to sound an alert across the state.

The DGP's office in Dehradun said the CCTV grab has been released on WhatsApp with an appeal to people to help track down the suspect seen with seven to eight persons standing close to him in the background who could be his associates.

An alert has been sounded in the state and a search launched to trace the suspect, a source at the DGP's office said. Coming close on the heels of the arrest of four terror suspects linked with ISIS from Roorkee in Haridwar district, the recovery of the CCTV grab assumes significance.