Shocking details have emerged with regard to the killing of the Uttar Pradesh police constable Suresh Vats by a violent mob in state's Ghazipur district on Saturday.

State police chief O P Singh said here on Sunday that so far 19 people, mostly workers of the Nishad (the boatmen community) Party, have been taken into custody, while 80 others have been booked in connection with the incident.

A massive hunt was launched to nab a senior office-bearer of the party, who the police said was the key suspect. The accused, however, is absconding.

According to sources, Vats, who was among the convoy of the police personnel returning after doing their duty at Prime Minister Narendra Modi's public meeting in Ghazipur town on Saturday, was beaten to the death by the mob, which comprised members of the 'Nishad' community. They were holding a 'dharna' demanding reservation and also the release of one of their leaders, who was detained by the police earlier in the day.

Sources said that the mob indulged in heavy stone-pelting as the police vehicles came near. As a result of which, the cops started to run for their safety. Vats was caught by the mob and hit with sticks and stones. 

"Vats could be rescued only after dozens of policemen reached there later... he succumbed to his injuries on the way to the district hospital," said a senior district police official in Ghazipur.

The police said that efforts were on to identify the attackers with the help of the video footage. 

The killing triggered a nationwide outrage, and the Opposition parties in the state slammed the state government for failing to protect the men in khaki. "When the cops are being killed, only god can protect the common citizens," said a senior state Congress leader.