A huge contingent of police and Rapid Action Force were deployed at the spot to control the situation. (Image for representation: ANI)

A man allegedly died in police custody in West Bengal's Malda district, sparking anger among locals who ransacked a police outpost and set it ablaze, a senior officer said on Monday.

The incident took place on Sunday late night at Milki police outpost and four police personnel were injured, he said.

"Ainul Khan (55), residing at Puratan Bhagabanpur area, and seven others were picked up from a gambling den on Sunday and Khan was taken to a primary health centre after he felt unwell at the outpost.

Ainul Khan was referred to Malda Medical College and Hospital but locals did not allow him to be taken to hospital alleging that he had expired due to police assault," district Superintendent of Police Alok Rajoria said.

The mob damaged one police vehicle and assaulted the officers, he said, adding that the attackers snatched the other accused persons and set the outpost on fire, resulting in damage of important documents.

During the incident, Ainul Khan died and four police personnel were injured, Rajoria said.

The dead body was sent for postmortem. "A raid was conducted and 15 people have so far been arrested. Such incident of attack on police cannot be accepted. Search operation will continue," he said.

A huge contingent of police and Rapid Action Force were deployed at the spot to control the situation, he added.