A gunfight between a suspected IS operative and commandos of the Uttar Pradesh Police's Anti-Terror Squad (ATS) was underway here on Tuesday, the police said.

The ATS, based on "concrete" information from intelligence, had gone to apprehend Saiful, suspected of involvement in the blast in a train in Madhya Pradesh, from a house in Haji colony of Thakurganj area when he suddenly opened fire on the team.

Following this, ATS commandos returned fire at Saiful, who was on the first floor. A senior ATS officer is heading the operation, a senior police official told media.

"We are trying to ensure that he is arrested alive and there is no collateral damage as this is a residential area," said another official.

At least eight persons were injured in an explosion in a passenger train, going to Ujjain from Bhopal, in Madhya Pradesh's Shajapur district on Tuesday, authorities said.