Sri Lankan authorities are investigating a grenade explosion in Trincomalee that killed five young Tamils and injured two others Monday.
Military spokesmen say the incident was a botched attempt to ambush a military patrol, and that victims of the blast may have been associated with Tamil rebel groups. No government soldiers were injured.
A pro-rebel Internet site, Tamilnet says the victims, all teenaged students, were at a popular beachside gathering spot Monday evening when unidentified men tossed explosives into a crowd.
Trincomalee, the major city in northeastern Sri Lanka, is under government control, but Tamil rebels based in nearby jungles have staged frequent operations in the area.
A truce in 2002 halted decades of conflict between Sri Lankan government forces and the country's separatist Tamils, but the cease-fire has been threatened by recent outbreaks of violence.