Baghdad, Iraq ? Insurgents hammered central Baghdad on Sunday with one of their most intense mortar and rocket barrages ever in the heart of the capital, heralding a day of violence that killed nearly 60 people nationwide as security appeared to spiral out of control.

At least 37 people were killed in Baghdad alone. Many of them died when a U.S. helicopter fired on a disabled U.S. Bradley fighting vehicle as Iraqis swarmed around it, cheering, throwing stones and waving the black and yellow sunburst banner of Iraq’s most-feared terror organization.

The airstrike, which the military said is under investigation, was captured on film when a correspondent for an Arabic-language television network was mortally wounded by shrapnel from the strike in the midst of taping a report. Reporter Mazen al-Tumeizi, 25, was talking into the camera, with flames and bystanders in the background, when a sharp blast buckled him forward. The camera swung away with blood on the lens, as al-Tumeizi yelled, “I am dying. I am dying.”

An Iraqi cameraman working for the Reuters news agency and an Iraqi freelance photographer for Getty Images were wounded.

Maimed and lifeless bodies of young men and boys lay in the street as the stricken U.S. vehicle was engulfed in flames and thick black smoke.

Across the country, the death toll Sunday was at least 59, according to figures from the Health Ministry, the Multinational Force command and local authorities.

Nearly 200 people were wounded, more than half of them in Baghdad.

Strong detonations again shook the center of Baghdad after sunset Sunday. There were no reports of damage or casualties.

As the early morning barrage was under way in Baghdad, insurgents attacked the infamous U.S.-run Abu Ghraib prison on the city’s western edge. Several mortar shells exploded outside the complex about 6 a.m., and about 20 minutes later a pickup truck packed with artillery shells crashed through the chain-link fence on the outer perimeter.

A U.S. soldier stands guard near a destroyed Humvee after a suicide attacker detonated a car bomb near it in Baghdad, Iraq. The crater made by the impact of Sunday's explosion is visible in the foreground. U.S. casualties were not known, although at least three civilians in a nearby car died.

Marines opened fire and the vehicle exploded before reaching the main security wall, killing the driver, a military statement said. Seven people were later arrested, it 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.

In an Internet 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.”

The statement’s source could not be verified, but the scope and intensity of the attacks raised serious questions about the state of security, which has deteriorated since the June 28 transfer of sovereignty to the interim Iraqi government.

In Basra, interim Prime Minister Ayad Allawi vowed to pursue insurgents.

“We are adamant that we are going to defeat terrorism,” Allawi said. “We intend to confront them and bring them to justice.”

Interior Minister Falah Hassan al-Naqib suggested the attacks could be in response to a government operation against the Adel neighborhood of west Baghdad, an insurgent hotbed. However, the scope of the attacks suggested they had been in preparation for some time.

Secretary of State Colin Powell acknowledged that the U.S.-led coalition faced a “difficult time” in Iraq but said the United States had a plan to quash the insurgency and bring those areas under control in time for national elections in January.

The insurgency “will be brought under control,” Powell said on NBC’s “Meet The Press.” “It’s not an impossible task.”

But Iraqi Foreign Minister Hoshyar Zebari said the level of security in his country will dictate whether the national elections are held when scheduled.

“The timetable really depends at the end of the day on the security situation,” Zebari said in Cairo, Egypt. “But we are going in this direction (of elections) without hesitation.”

Near Hillah, 60 miles south of Baghdad, three Polish soldiers were killed in an ambush — raising Poland’s death toll in Iraq to 13 — and a bomb killed three Iraqi national guardsmen. A district police chief was killed in an attack in Baghdad’s Yarmouk neighborhood.

Meanwhile, 10 people were killed and 40 were wounded in fighting in the insurgent stronghold of Ramadi, 70 miles west of Baghdad, said hospital director Abdel Munim Aftan.

Three American soldiers and two Iraqi civilians were wounded Sunday when a suicide driver blew up his car next to a U.S. Army convoy on the road to Baghdad International Airport, American sources said. The vehicle was one of seven car bombs reported Sunday in Iraq, two of which did not explode, the sources said.