Militants killed three Indian policemen in the Kashmir valley after storming into a police camp on Saturday in their biggest strike on a government compound in the disputed region in nearly a year.
One of the militants, who entered the camp in Pulwama town of southern Kashmir, was also killed in the ensuing gunfight, said a senior Indian army officer who declined to be named.
The army and police are jointly trying to dislodge the militants and have evacuated families from the camp's residential block, Lieutenant General J S Sandhu of the Indian army told reporters.
The attack on the police complex is the biggest on a state security facility since September 18 last year, when armed militants broke into an army camp near the de facto border, called the Line of Control (LoC), in Uri, killing 18 army personnel.
The exact number of militants inside the compound is not known, India's federal home ministry said in a statement.
Indian troops have killed 134 militants, including 7 top commanders, this year, officials said. Majority of these militants were eliminated in the last two months after security forces doubled down on an offensive in south Kashmir and along the LoC.
Last year, 150 militants were killed in Kashmir.
About 79 militants crossed the LoC into Indian Kashmir in July, according to Indian officials.
India accuses Pakistan of training and arming militants, and helping them infiltrate across the LoC dividing Kashmir. Pakistan denies those allegations.
The South Asian rivals fought two of their three wars since independence in 1947 over Muslim-majority Kashmir, which they both claim in full but rule in part.