PATHANKOT, India (AP) -- Indian security forces on Sunday continued to try to secure a major air force base near the border with Pakistan where an attack by suspected militants left at least 11 people dead, amid reports of fresh gunfire at the compound.

The attack on the Pathankot air force base, which started before dawn Saturday, left seven Indian troops and four gunmen dead, and is seen as an attempt to undo recent improvements in the relationship between archrivals India and Pakistan.

Combing operations were continuing at the base Sunday, air force spokeswoman Rochelle D'Silva said. Officials gave no other details about the situation at the base, but by late Sunday afternoon there was no word that it had been secured.

At least one grenade blast was heard from inside the compound Sunday morning and several television channels reported that there was fresh gunfire later in the day. At least seven trucks with soldiers and several armored vehicles were seen entering the base, but officials declined to comment.

Since Saturday morning, the base has been swarming with air force commandos, troops from India's elite National Security Guard and local police.

The number of troops killed in the attack rose to seven on Sunday, after four soldiers succumbed to their injuries overnight and another died after being wounded in an explosion, officials said.

D'Silva gave no details about the death of an elite commando Sunday morning, except to say that he was seriously wounded in a blast. News reports said the commando was killed while defusing explosives. More details are expected from a press briefing by India's home secretary later Sunday.

The attack at one of India's major air force bases started a few hours before dawn Saturday when a group of militants entered the area of the base where the living quarters are located, the Defense Ministry said. The gunbattle _ which lasted about 14 hours _ came just a week after Indian Prime Minister Narendra Modi made a surprise visit to archrival Pakistan and met with his Pakistani counterpart, Nawaz Sharif.

It was the first visit to Pakistan in 12 years by an Indian prime minister and marked a significant thaw in the mostly tense relations between the nuclear-armed neighbors.

The two leaders also held an unscheduled meeting at the Paris climate change talks last month.

The sprawling Pathankot air force base is spread over several kilometers, including some forested sections. It houses a fleet of India's Russian-origin MiG-21 fighters and Mi-25 and Mi-35 attack helicopters, along with other military hardware.

The Defense Ministry said no aircraft or military equipment was damaged in the fighting.

The base is on the highway that connects India's insurgency-plagued Jammu and Kashmir state with the rest of the country. It's also very close to India's border with Pakistan.

The Himalayan region of Kashmir is divided between India and Pakistan, but is claimed in its entirety by both. Rebels in India's portion of Kashmir have been fighting since 1989 for independence or merger with Pakistan.

India accuses Pakistan of arming and training the insurgents, a charge Islamabad denies, and the attack at the base was seen as a possible attempt to unravel recent progress in the relationship between the two nations.

Ahead of Modi's Dec. 25 visit to Pakistan, the national security advisers of both countries had met in Thailand. The foreign secretaries of both nations are scheduled to meet in Islamabad later this month.

The responses to Saturday's attack from both countries have been muted so far, with neither New Delhi nor Islamabad giving any indication that the planned talks are under any threat.

In Pakistan, Sharif's foreign affairs adviser, Sartaj Aziz, said in a radio interview Saturday that Pakistan wants to consolidate its improved relations with India. Pakistan's foreign ministry condemned the attack.

The reaction in India has also been quiet so far. While all political parties condemned the attack, there was no immediate demand that the government call off talks with Pakistan. In the past, when it was in opposition, Modi's own right-wing Bharatiya Janata Party has been the most vocal critic of engagement with Pakistan, saying that talks and terror should not go together.

But with Modi's own diplomatic engagement with Islamabad at stake, the BJP has given no indication yet that the planned talks have been threatened by the attack.

Police have said they're investigating whether the gunmen came from the Indian portion of Kashmir, where rebels routinely stage attacks, or from Pakistan.

The death of seven Indian troops came despite the fact that the Defense Ministry said that there had been intelligence reports about a likely terror attack on military installations in Pathankot, and that the air force had been prepared to thwart any attackers.