The Sri Lankan navy waged a short sea battle with Tamil Tiger militants Saturday evening, quickly sinking two rebel boats and killing six people on board, the military said. The fighting occurred about 20 kilometers (10 miles) off Sri Lanka's northwest coast, when naval vessels ordered two small boats they suspected of belonging to the rebels to stop and then fired warning shots, said naval spokesman D.K.P. Dassanayake. The boats responded by firing a rocket propelled grenade. The navy fired back and sank them, he said. Sailors said a total of 10 people on the two boats, he said.