Two of London's busiest bridges were closed Thursday and roads cordoned off after a suspected World War II bomb was found in the River Thames.

The Metropolitan Police force said officers were called Thursday afternoon "to reports of suspected World War II ordnance in the river."

Police said roads in the area were closed, including the northbound lanes of Waterloo Bridge and all of Westminster Bridge, near the Houses of Parliament. Nearby Westminster subway station also was shut.

The force said specialist officers were assessing the device.

London was heavily bombed by Nazi Germany during the war, and unexploded munitions are still sometimes found.