BAGHDAD - A suicide bomber targeting a police checkpoint in Baghdad killed at least three people while car bombs hit army and police patrols in two other cities, killing three others, police and hospital sources said on Sunday.

The attacks were the first serious violence since mid-April when a wave of bombings killed 36 people across the country, including an attack involving three car bombs and a suicide bomber in which 15 people died in Baghdad.

Police opened fire on Sunday when the suicide bomber refused their orders to stop at a checkpoint in the western Baghdad district of Mansour before he detonated his load, killing three officers, authorities said.

"It was a suicide bomber. The checkpoint guards told him to stop and he didn't, so they shot at him," said Raad Latif Hussein, an officer with a Baghdad police rescue unit.

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