A roadside bomb targeting a foot patrol exploded in Sri LankaÂ’s restive east Wednesday, killing two village guards and wounding three police commandos, the military said, blaming separatist Tamil rebels for the blast. The blast came a day after Tamil Tiger rebel planes bombed government positions in northern Sri Lanka in their second-ever airstrike in more than two decades of war. Military spokesman Brig Prasad Samarasinghe said the insurgents targeted the group of commandos and guards who were patrolling in Ampara district. There was no immediate comment from the rebels, who are fighting to create a separate homeland for Sri LankaÂ’s ethnic Tamil minority in the north and east. The blast and this weekÂ’s air raid come amid rising fears that the government may be preparing a major assault on rebel strongholds in the north.