PATHANKOT, India - A gold medal-winning shooter was among 10 people killed in an audacious pre-dawn assault on an air force base, officials said on Sunday as troops worked to clear the compound in Pathankot, Punjab near India's border with Pakistan after a 15-hour gunbattle.

Six Indian security personnel were killed and the bodies of four militants had been recovered after the assault on the heavily fortified Pathankot air base.

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.

One of the Indian security members killed in the attack was Subedar Fateh Singh, who won gold and silver medals in the first Commonwealth Shooting Championships held in 1995, the National Rifle Association of India said.

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.