Firefighters hose down burning vehicles following an explosion Saturday in a crowded commercial area near the Imam Hussein shrine in Karbala, 50 miles south of Baghdad. A parked car exploded Saturday near one of Shiite Islam's holiest shrines as people were headed to the area for evening prayers.

Baghdad, Iraq ? A car bomb exploded Saturday in the Shiite holy city of Karbala as the streets were packed with people heading for evening prayers, killing at least 58 and wounding scores near some of the country’s most sacred shrines. Separately, the U.S. military announced the deaths of nine American troops, including three killed Saturday in a single roadside bombing outside Baghdad.

With black smoke clogging the skies above Karbala, angry crowds hurled stones at police and later stormed the provincial governor’s house, accusing authorities of failing to protect them from the unrelenting bombings usually blamed on Sunni insurgents. It was the second car bomb to strike the city’s central area in two weeks.

Near the blast site, survivors frantically searched for missing relatives. Iraqi television showed one man carrying the charred body of a small girl above his head as he ran down the street while ambulances rushed to retrieve the wounded and firefighters sprayed water at fires in the wreckage, leaving pools of bloody water.

The blast took place about 7 p.m. in a crowded commercial area near the shrines of Imam Abbas and Imam Hussein, major Shiite saints.

Security officials said the car packed with explosives was parked near a cement barrier intended to keep traffic away from the shrines, which draw thousands of Shiite pilgrims from Iran and other countries.

That suggested the attack, which occurred two weeks after 47 people were killed and 224 were wounded in a car bombing in the same area on April 14, was aimed at killing as many Shiite worshippers as possible.

Salim Kazim, the head of the health department in Karbala, 50 miles south of Baghdad, said 58 people were killed and 168 wounded. The figures were confirmed by Abdul-Al al-Yassiri, the head of Karbala’s provincial council.

“I did not expect this explosion because I thought the place was well protected by the police,” said Qassim Hassan, a clothing merchant who was injured by the blast. “I demand a trial for the people in charge of the security in Karbala.”

The Americans killed in Iraq included five who died in fighting Friday in Anbar province, three killed when a roadside bomb struck their patrol southeast of Baghdad and one killed in a separate roadside bombing south of the capital.

The U.S. military has warned that such bombings were intended to provoke retaliatory violence by Shiite militias, whose members have largely complied with political pressure to avoid confrontations with Americans during the U.S. troop buildup.