BAGHDAD, Iraq – One of Saudi Arabia’s most-wanted terrorist was killed by a U.S. air strike in northwestern Iraq, the leader of Al Qaeda in Iraq said, and four car bombs outside Shiite mosques in Baghdad killed 15 and wounded 28 yesterday, police said.

The latest violence followed a series of car bombs late Wednesday, including four exploding within minutes of each other. At least 23 people were killed in western Baghdad’s Shula neighborhood and a nearby suburb, bringing the death toll over a 12-hour span to 40.

The Web statement said Abdullah Mohammed Rashid al-Roshoud was killed in fighting near Qaim, on the border with Syria. It was signed by Abu Musab al-Zarqawi, the most notorious terrorist leader in Iraq.

The statement did not say when al-Roshoud was killed, but American forces have launched a series of offensives near Qaim in past weeks against militants coming across the border.

Al-Roshoud slipped into Iraq in April, according to the posting, the authenticity of which could not be confirmed.

The Saudi militant and a group of mujahedeen “killed some of the Crusaders until the enemies of God had to withdraw,” it said.

“When the Crusaders could not enter the area, the only thing they could do was bombard the mujahedeen with warplanes,” it said. “Our sheik [al-Roshoud] got what he wished” – martyrdom.

Al-Roshoud had been no. 24 on a list of the 26 most-wanted terrorist leaders put out by Saudi Arabia two years ago and was one of only three militants on the list still at large. He was one of the main theologians for Al Qaeda’s network in Saudi Arabia, calling for a holy war against the Saudi royal family and Western interests in the Persian Gulf.

Most residents of the two Baghdad neighborhoods that were attacked are from Iraq’s Shiite majority, while the insurgents are almost exclusively Sunni Arabs, a minority that dominated Iraq until Saddam Hussein’s ouster two years ago.

The explosions both days were carried out at times when large crowds were on the capital’s streets. Wednesday night’s bombs came hours before an 11 p.m. curfew, when many residents are out at eateries or chatting on the streets before locking themselves inside their homes.

The militant group Ansar al-Sunnah Army said in a Web statement that it was responsible for the Shula blasts.

Yesterday’s twin explosions took place when many are just beginning their daily routines. Five police officers were among the 15 dead.

A young boy, his left leg missing from below the knee, sat on the sidewalk near a mangled bicycle, screaming as a man tried to comfort him. The force of the blasts blew off store shutters, and the surrounding sidewalks were covered with debris, including shattered glass, concrete slabs, and charred vegetables and fruit. A few trees were toppled, scattering leaves on the sidewalk.

A pre-dawn raid led by American troops destroyed a hideout in Baghdad used by extremists associated with Mr. al-Zarqawi, the military said. The attack killed at least six insurgents who opened fire on the troops, the military said. Troops seized weapons, ammunition, and explosives.

Separately, a car bomb detonated by remote control hit an Iraqi police patrol in Tuz Khormato, north of Baghdad, killing one policeman and wounding seven civilians, police Brigadier General Sarhad Qadr said. Tuz Khormato is 55 miles south of the northern city of Kirkuk.