Baghdad, Iraq ? Insurgents hit a U.S. base in central Iraq with mortar shells, killing one American soldier and wounding two others, the military said Saturday. In a separate attack, rebels set off a bomb and opened fire on a U.S. convoy in Baghdad, killing two soldiers and wounding three.

The mortar shells struck a base of the Army’s 4th Infantry Division on Friday night in Balad, north of Baghdad, Sgt. Robert Cargie said.

One shell exploded near a trailer used as a bedroom by some troops, and a soldier standing in its doorway was killed, he said. Two other soldiers were struck by shrapnel and taken to a combat support hospital, where they were in stable condition, Cargie said.

The U.S. military searched for the assailants by helicopter and set up checkpoints in the area. Six people were detained for questioning, a military spokesman said.

In a separate attack Friday in Baghdad, a bomb exploded in the al-Rashid district and insurgents opened fire on a U.S. convoy, killing two U.S. soldiers and wounding three others, the military said.

The names of the slain soldiers were withheld pending notification of family.

Northwest of Baghdad, hundreds of residents protested Saturday in Hadithah, saying U.S. soldiers had raided the town overnight. A cameraman for Associated Press Television News filmed four shroud-covered bodies and one person in a hospital who was injured by a gunshot.

Residents said the four died in the U.S. raid, but there was no way to immediately verify the claim. The military had no immediate comment.

The soldiers were in armored vehicles and “targeted three houses — my sister’s house, my uncle’s and my own,” said Abdel Meguid Awad, a resident.

Hadithah is part of the so-called “Sunni Triangle,” the former heartland of Saddam Hussein’s support and a center of opposition to the U.S.-led occupation. The American search for fugitives and insurgents is focused on the region.