PATHANKOT: The number of troops killed in an attack on an Indian air force base rose to seven on Sunday, after four soldiers succumbed to injuries sustained in the hourslong gunbattle near the border with Pakistan and another died after being wounded in an explosion, officials said.

Four suspected militants were killed in the fighting on Saturday.

Gunfire and blasts were heard a second consecutive day on Sunday, and Indian TV channels reported two gunmen were still at large in the sprawling facility.

News channels cited police in northwestern Punjab as saying the two gunmen were still holed up in the Pathankot air base, more than a day after the pre-dawn raid in which four attackers and two Indian military personnel were killed.

A home ministry official said several blasts had been heard in the facility but could not confirm reports that gunmen were still at large.

Air force spokeswoman Rochelle D'Silva said that combing operations to secure the Pathankot air force base were continuing late Sunday morning. Officials gave no other details about the situation at the base.

Earlier in the day, at least one grenade blast was heard from inside the base, but officials declined to comment.

D'Silva gave no details about the death of an elite commando Sunday morning, except to say that he was seriously wounded in an explosion. News reports said the commando was killed while defusing explosives.

A gold medal-winning Indian shooter was among the troops killed. Subedar Fateh Singh won gold and silver medals in the first Commonwealth Shooting Championships held in 1995, the National Rifle Association of India said.

The attack by gunmen disguised as soldiers came a week after Indian Prime Minister Narendra Modi made an unscheduled visit to Pakistani counterpart Nawaz Sharif in an effort to revive talks between the nuclear-armed neighbours.

Officials said the attack on the military base, just 25 km (15 miles) from the border with Pakistan, bore the hallmarks of previous suspected assaults by Pakistan-based militant groups, underscoring the fragility of recent efforts to revive bilateral talks between the often uneasy neighbours.

There was no immediate claim of responsibility.

Pakistan condemned the attack and said it wanted to continue to build on the goodwill created by the impromptu meeting between Modi and Sharif last month.

Two security personnel were wounded in a blast on Sunday, a police official in Pathankot said, as troops scoured the base.

Dozens of armed forces stood guard outside the base.

Home Minister Rajnath Singh had said on Saturday five militants had been “neutralised”, but there were no reports yet of the body of the fifth attacker being found.

In New Delhi, two trains were delayed early on Sunday after officials received information about a possible bomb threat on a train running between the capital and Lucknow to the southeast, railways spokesman Neeraj Sharma said.

Trains were deemed safe and were running on schedule by mid-morning, Sharma said.