U.S. Defense Secretary Donald Rumsfeld has returned from a surprise visit to Iraq where he visited troops on Friday in Tikrit, Mosul, Falluja and Baghdad.

On the day of his visit, a fuel truck exploded in a suicide bombing in the affluent al-Mansour neighborhood, a police official said.

Rumsfeld was in Baghdad for part of his one-day Iraq trip but was believed to have left the country before the explosion.

Rumsfeld did not go to the al-Mansour district, which has been the site of previous attacks and abductions of Americans and other foreigners.

The blast killed at least nine people, wounded 20 others and set six buildings on fire, according to hospital officials.