Uttar Pradesh police have claimed that Thursday’s violence in Lucknow was committed by “rioters who belonged to Malda” in Bengal but sources said the parents of the six arrested suspects had migrated to the north Indian state three decades ago.

“We have nabbed people and collected evidence from the violence site that prove that some of the rioters belonged to Malda,” O.P. Singh, the Uttar Pradesh director-general of police, told reporters in Lucknow on Sunday.

The Lucknow incident had claimed one life. The young man was one of the 16 people killed in Uttar Pradesh during the protests against the amended citizenship bill and the NRC.

Uttar Pradesh deputy chief minister Dinesh Sharma said: “There is involvement of the Popular Front of India. They have a connection with Simi (a banned outfit). Six people from Malda have been arrested.”

However, a resident of Lucknow West, where the six suspects live, said they worked there as labourers.

“The six youths, in their 20s, were born in Lucknow. Their parents had arrived from Malda three decades ago and settled here with the help of a BJP leader. He had given them ration cards. They used to vote for the BJP leader. These youths did not participate in the protest. The police picked them up from their homes on Thursday night,” the resident said.

Some officials suggested that the police were flagging the “Bengal link”, however tenuous it might be, to please their political masters who are miffed with Mamata Banerjee for sending a delegation of MPs to Uttar Pradesh after the violence. They were detained at the Lucknow airport on Sunday.

Uttar Pradesh DGP Singh is due to retire on January 31, 2020. In February, the post of chief information commissioner is scheduled to fall vacant. A government source confirmed that the 1983-batch IPS officer was among the applicants.

DGP Singh underscored that the police were in a position to substantiate the claim that outsiders had sneaked into the protests and indulged in violence at Parivartan Chowk in Lucknow on Thursday. “The spent cartridges recovered from the spot also suggest that the violence was meticulously planned,” Singh said.

A police source later said: “We found some identity cards belonging to the rioters from Parivartan Chowk that bore addresses in Malda. We arrested them on the basis of those identity cards.”

Asked whether outsiders had sneaked into the protests at other places, the police source said: “No, at other places local people were committing violence.”

Another officer said: “We traced them with their mobile phones which were found at the violence site. There were SMSes in Bengali.”