Iraqi officials say more than 50 people, including many children, were killed Wednesday in a series of explosions in or near the southern city of Basra.

Officials say scores of others were wounded in the blasts that occurred during morning rush hour. They say near simultaneous explosions targeted three police stations in Basra -- Iraq's second largest city. Another explosion hit a police academy in the town of Zubayr, just south of Basra.

A British military spokesman said the blasts appeared to have been caused by car bombs. The spokesman said the explosion in Zubayr left at least three Iraqis dead and two British soldiers wounded.

Meanwhile, in the volatile city of Fallujah, west of Baghdad, U.S. Marines exchanged gunfire with insurgents early Wednesday morning, despite a tentative ceasefire.

Residents say at least six civilians were killed and 10 others wounded in the fighting that lasted for four hours.

Tuesday, U-S Defense Secretary Donald Rumsfeld told reporters at the Pentagon that the current military standoff in Fallujah can not continue indefinitely.

Earlier this week, a deal reached to try to defuse the stand off. Under the deal U.S. Marines agreed not to begin further military offensives in Fallujah, if insurgents turn in their illegal heavy weapons.

Some information for this report provided by AP, AFP and Reuters.