Two car bombs exploded Wednesday in northern and eastern Baghdad. One woman was killed and 15 people, many of them schoolboys, were injured in a car bombing in a religiously mixed area of eastern Baghdad, police said. Thirteen people were injured in the other car bombing in the Shiite area of Shulah in the north of the city.

Two Sunnis — a professor and an ambulance driver — were killed Wednesday in the mostly Shiite southern city of Basra, police said. A Sunni organization said all Sunni mosques in Basra would close for 48 hours to demand the authorities put an end to the killings.

In Baghdad, police said they found the bodies of two men dumped in separate areas of the city late Tuesday. Police also found a body — handcuffed, blindfolded and shot — early Wednesday in Iskandiriyah, 30 miles south of Baghdad, according to police Capt. Muthana Khalid.

Gunmen opened fire Wednesday on the offices of the Iraqna mobile telephone company in the Mansour area, killing two security guards and injuring three others, police said.

A civil engineer was shot to death Wednesday in front of a barber shop in west Baghdad, police said. Gunmen also assassinated a school superintendent in front of a girl's school in southeastern Baghdad, police said.

Elsewhere, U.S. and Iraqi troops freed three Iraqi kidnapping victims in the northern city of Tikrit, U.S. officials said.

Also Wednesday, U.S. and Iraqi troops raided several buildings in Youssifiyah southwest of Baghdad, killing one insurgent and capturing nine others, the U.S. command said. The raid occurred three days after a U.S. Apache attack helicopter was shot down near Youssifiyah, killing the two crew members.