BAGHDAD, Iraq (AP) -- Militants pounded central Baghdad on Sunday with one of their most intense mortar barrages ever, targeting the Green Zone and destroying a U.S. vehicle along a major street. At least 25 people were killed and more than 100 were wounded - some of them when a U.S. helicopter fired at crowds around the burning vehicle.
Elsewhere, a suicide attacker detonated an explosives-packed vehicle at the gates of Abu Ghraib prison, killing himself but causing no other casualties, the U.S. military said. American guards fired at the vehicle before the driver could reach the gate, the military said.
Tawhid and Jihad, a militant group linked to al-Qaida and led by Jordanian terror mastermind Abu Musab al-Zarqawi, said it carried out Sunday's coordinated campaign of violence in Baghdad - the Abu Ghraib bombing, the mortar barrage and attacks on central Haifa Street.
In a Web statement, the group boasted that it holds the initiative in the Iraqi insurgency and possesses the "capability to surprise the enemy and hit its strategic installations at the right time and place."
Rockets and mortars began raining down before dawn on the Green Zone, which houses Iraqi and U.S. offices, and other parts of central Baghdad. As the shelling continued after sunrise, U.S. troops backed by armored vehicles moved into the streets searching for the attackers.
A Bradley fighting vehicle rushing down Haifa Street to assist a U.S. patrol was disabled by a car bomb about 6:50 a.m., the U.S. military said. The four U.S. crewmen escaped with minor injuries but came under small arms and rocket-propelled grenade fire and called for air support, U.S. officials said.
Jubilant fighters and young boys swarmed around the burning vehicle, dancing, cheering and hurling firebombs. Several young men placed a black banner of Tawhid and Jihad in the barrel of the Bradley's main gun.
Suddenly, a U.S. Kiowa helicopter fired on the Bradley, trying to destroy it to prevent insurgents from looting weapons and ammunition on board, the military said.
Witnesses said several people milling around the Bradley, including a correspondent for the Arabic language Al-Arabiya television station, were killed. An Iraqi cameraman working for the Reuters news agency was also injured.
Al-Arabiya broadcast videotape showing its employee, Mazen al-Tumeizi, preparing to make a report. Suddenly, an explosion occurred behind him. He doubled-over and began screaming "I'm dying, I'm dying" and colleagues tried to help him.
Health Ministry official Saad al-Amili said 13 people were killed and 61 wounded on Haifa street, though it was not clear how many were killed in the helicopter strike. Scattered shoes, pools of fresh blood and debris littered the street.
Another 12 people died and 41 injured Sunday in other violence across the city, al-Amili said.
"We were standing near the destroyed vehicle when the helicopter started firing, so we rushed to safety in a nearby building," Alaa Hassan, 24, said from his hospital bed. "I went back to the scene to help the wounded people when the helicopter fired again and I was hit in the chest."
The Tawhid and Jihad claim of responsiblity for Sunday's fighting came in a posting on its Web site. Al-Zarqawi, one of the most wanted militants in Iraq, is believed to be behind a number of suicide bombings in Iraq over the past year.
On June 24, his group claimed responsibility for a surprise offensive of bombing and shooting attacks in four northern cities on June 24 that killed more than 100 people. Tawhid and Jihad - Arabic for "monotheism and holy war" - has also beheaded several foreign hostages in Iraq in recent months.
In other violence:
- The police chief in the west Baghdad district of Yarmouk was killed Sunday in a bomb attack while on patrol in the district, the Interior Ministry said. Col. Alaa Bashir and another officer died on the spot, said ministry spokesman Col. Adnan Abdul-Rahman.
- Two powerful bombs exploded simultaneously Sunday on a road near Hillah in central Iraq, killing at least three Iraqi National Guard members and seriously wounding three others, a Polish military spokesman said.
- Clashes occurred in the Sunni insurgent stronghold of Ramadi, 70 miles west of Baghdad, killing two people and wounding 20 others, hospital officials said. A U.S. Humvee was ablaze, parts of it scattered across the street, witnesses said.
A bomb also exploded along a road just west of Ramadi as a U.S. military convoy was passing by, witnesses said. They said U.S. troops opened fire after the attack, wounding several people in the area. It was not immediately clear whether there were any American casualties.
- Gunmen attacked security forces guarding oilfields in two separate incidents in northern Iraq, injuring five officers, officials said.
Three officers were wounded when attackers opened fire as they stood guard near the Dibis oilfields northeast of the city of Kirkuk, while two others were injured in a drive-by-shooting west of Kirkuk, said Maj. Gen. Anwar Mohammed Amin of the Iraqi National Guard.
Security officers guarding the oil-rich Kirkuk area have repeatedly been targeted by militants who have blown up scores of pipelines in a bid to disrupt reconstruction efforts and undermine the U.S.-backed interim government.