A suspected mastermind of last week's devastating attack in Musayyib (search) was captured during a raid by Iraqi forces in which two of his associates were killed, police said Saturday.

Musayyib's police chief, Lt. Col. Ahmed al-Shammari (search), told the Dubai-based Al Arabiya television that the suspect was captured in a raid in the nearby town of Jarf al-Sakhr but he did not say when it took place.

The prisoner, who was not identified, confessed to having stolen a tanker truck, then to taking it to Musayyib to kill "the biggest number of people," al-Shammari said. He did not say whether a suicide driver actually carried out the attack as some witnesses said earlier.

The July 16 attack in front of a Shiite mosque (search) in Musayyib, about 40 miles south of Baghdad, killed nearly 100 people, the Iraqi government said. It was one of the deadliest attacks since the fall of Saddam Hussein's regime in April 2003.