MANAGUA, NICARAGUA, FEB. 5 -- A truck carrying civilian passengers was ambushed by Nicaraguan rebels, or contras, yesterday, killing 16, witnesses and hospital officials said.

Authorities in the hospital in the northern city of Esteli said at least 16 more of about 60 passengers were injured.

The truck, normally used to carry passengers, was traveling its regular route toward the town of Quilali in Nueva Segovia province when it came under rifle fire at about 5 p.m., witnesses said. Land mines also appear to have been used in the attack, since some of the victims' wounds were caused by shrapnel and explosives, doctors said.

Among the dead were at least six children, a 10-year-old boy and five infants, according to a list compiled by Witness for Peace, an American religious human rights organization that gathers information about civilian casualties in contra attacks.

"I saw some contras, wearing camouflage uniforms. Why did they ambush us if we were in a civilian bus?" asked Bertilda Rivera, 16, a survivor with a punctured lung, as she lay on a stretcher at Manolo Morales Hospital in Managua.

Paddy Lane, a Witness for Peace volunteer in Esteli, said that two Sandinista soldiers were on board the bus. It was unclear if they returned fire.