A wave of pitched battles, bombings and an airstrike killed at least 23 people across northern Sri Lanka, the military said Monday, as a Japanese envoy met with officials to try to stop the raging civil war. In one attack, a roadside bomb hit a van in the Vavuniya region, just south of the front lines separating government forces from the Tamil Tiger rebels' de facto state in the north, military spokesman Brig. Udaya Nanayakkara said. The passengers, civilian workers with a military escort, were returning from an army base after collecting explosives for use in civilian metal mining, he said. The civilian driver and two soldiers were killed, while three other soldiers and a civilian were injured, the military said. The explosives inside the van did not detonate, Nanayakkara said.