The policemen were killed while on highway patrol in Awantipora, some 32 kilometres (20 miles) from the main city of Srinagar.[break]
Police said the guerrillas appeared to have approached the road by river and staged the attack.
"We´re ascertaining exactly what happened," police inspector general Abdul Gani Mir told AFP.
No militant group immediately claimed responsibility for the attack in the scenic Himalayan region.
A recent spike in militant attacks in Kashmir has caused alarm in India.
Last week, a top Kashmiri police official warned that militancy could intensify in the disputed area, with India saying some 80 militants recently crossed the border from Pakistan.
Firing along the disputed Line of Control (LoC), the heavily militarised border that divides Kashmir between India and Pakistan, has been among the heaviest since a ceasefire agreement in 2003.
About a dozen rebel groups have been fighting Indian forces since 1989 for independence or merger with Pakistan.
The fighting has left tens of thousands of people, mostly civilians, dead.
India and Pakistan have fought three wars since their independence from Britain in 1947, two of them over Kashmir.
Related story
Militants kill two police in Kashmir ahead of India's Independe...
