Prime Minister Nouri al-Maliki arrived early Wednesday to meet with local officials trying to restore order and move the hordes of pilgrims away from the beleaguered city.
The pilgrims were ordered to leave the area of the shrines, and armored Iraqi army Humvees drove slowly through the largely deserted area during the morning saying over loudspeakers that anyone caught there would be arrested.
Security officials said Mahdi Army gunmen loyal to radical cleric Muqtada al-Sadr on Tuesday fired on guards around two shrines protected by the Badr Brigade, the armed wing of the Supreme Islamic Iraqi Council.
Residents of Karbala contacted by telephone said snipers were firing on Iraqi security forces from rooftops. Explosions and the rattle of automatic weapons fire could be heard during telephone calls to reporters Tuesday in the city 50 miles south of Baghdad.
Officials reported 51 dead and 247 injured on Tuesday, but the city council member said Wednesday that 38 had been killed and 231 injured.
The clashes appeared to be part of a power struggle among Shiite groups in the sect's southern Iraqi heartland, which includes the bulk of the country's vast oil wealth.
Interior Ministry spokesman Maj. Gen. Abdul-Karim Khalaf said entrances and exits to Karbala "have been secured and more forces are on the way from other provinces." Officials said buses were sent to evacuate pilgrims from the city, which includes some of the world's most sacred Shiite shrines.
Gunfights also broke out Tuesday between Mahdi militiamen and followers of the Supreme Council in at least two Shiite neighborhoods of Baghdad and in Kut, about 100 miles (160 kilometers) southeast of the capital, police said.
Extra police took up positions in the center of another Shiite city, Diwaniyah, after gunmen fired on a mosque associated with the Supreme Council, police said. A curfew was clamped on the Shiite city of Najaf after a mortar round exploded on a major square, causing no casualties, officials said.