KABUL, Afghanistan - -A powerful truck bomb on Thursday killed at least 25 people, more than half of them children, in an eastern province near Kabul. Authorities speculated that the explosives-laden vehicle was intended for an attack in the capital.
Three American soldiers were killed by roadside bombs, the U.S. military said, two in southern Afghanistan and one in the east.
The incidents followed a pattern of escalating violence in widely scattered areas of Afghanistan.
The truck blast took place in Lowgar province. The vehicle, traveling on Afghanistan's main north-south highway, apparently ran off the road and overturned before dawn. When police and civilians approached after daybreak and tried to right the truck, it blew up, the Interior Ministry said.
Most of the dead were civilians, including at least 13 students from a nearby primary school, local officials said. The thunderous blast left a huge crater in the highway, hurled debris over a wide area and demolished several nearby shops and homes.
The truck was piled high with a load of timber, with the payload of explosives buried underneath, police said. Officials were trying to determine whether the bomb had been triggered remotely when police and other help arrived or if it detonated when the truck was moved.
Ghulam Mustafa, the Lowgar police chief, said the truck's driver had disappeared, and officials were looking into the possibility that the Taliban had been in the midst of transporting the explosives to the capital.
Kabul has been relatively calm lately. However, an explosion of this size and strength in a crowded area such as the capital probably would have caused many more deaths and injuries.
During the past year, Lowgar gradually has become a hotbed of insurgent activity, alarming Western military officials and fostering the impression that the Taliban were tightening a noose around Kabul. Travelers on the main road south out of the capital face constant danger of ambush, abduction or banditry when passing through the province.
In an effort to weaken militants' grip on the area, U.S. troops from the 10th Mountain Division, based in Fort Drum, N.Y., have been deployed in Lowgar and adjoining Wardak province for about six months. In addition, a "village guards" initiative has been set up in the two provinces, which Afghan and Western authorities say eventually might be expanded countrywide.
Under the program, Afghan residents work as a kind of auxiliary police force to try to keep the insurgents from overrunning remote villages.
The latest bloodshed coincided with a major U.S. military offensive in southern Afghanistan's Helmand province, which is a center of both the insurgency and the opium trade. In the past week, about 4,000 U.S. Marines have secured the lower Helmand River Valley.