At least 14 people were killed and 38 wounded Monday night when a powerful bomb exploded in a Shiite mosque here, police officials said.

A woman who apparently planned to set off explosives in Shiite mosques was arrested.

Because the site was a Shiite mosque, the bombing is presumed to have been the work of Sunnis.

Residents said the attack was likely to have been retribution for the bombing of a Shiite mosque in the same neighborhood last week.

On May 7, 22 people were killed when a suicide bomber attacked a Shiite mosque.

In July 2003, gunmen killed more than 50 worshipers at a Shiite mosque.

In the two and a half years before then, going back to August 2003, there were only 80 attacks on Shiite mosques, the report said.

On Saturday night, a car bomb outside a Shiite mosque in Baghdad killed at least three people.

This vigilantism appeared to come as retribution for the bombing of a Shiite mosque the day before.

Insurgents have driven car bombs into Shiite mosques and restaurants.