The U.S. military on Saturday fired missiles at a target about 50 yards away from the general hospital in Baghdad's Sadr City district, wounding more than 20 people and destroying ambulances, hospital officials said.
Dr. Ali Bustan al-Fartusee, director general of Baghdad's health directorate, told The Associated Press that 23 civilians were injured.
He said no patients in the hospital were hurt, but that some of the wounded included civilians outside on their way to visit patients, and that around 17 ambulances were damaged.
Earlier, hospital officials said 28 people were injured; the reason for the discrepancy was not immediately known.
The missile were fired from a launcher on the ground, the U.S. military said. It said in a press release that it destroyed a "criminal element command and control center" with missiles in northeastern Baghdad — where Sadr City is located — around the same time Iraqis reported the attack near the hospital.
The U.S. military also said that American forces "only engage hostile threats and take every precaution to protect innocent civilians."
Shiite extremists are known to have operated in a building next to the hospital, according to local reporters.
The attack left a crater just outside the concrete barriers of the hospital and badly damaged several ambulances and some other vehicles, AP Television News footage showed. The explosion also demolished a brick building.
U.S. and Iraqi forces have been locked in street battles with Shiite militias since late March in Sadr City, a Baghdad slum of 2.5 million people and the base of anti-American Shiite cleric Muqtada al-Sadr's militia, the Mahdi Army.
Deadly clashes in Sadr City
More than 100 people have been injured in fighting since Friday in Sadr City, Iraqi health officials said.
The U.S. military said Saturday that 10 militants were killed in fighting on Friday, including a sniper and a triggerman accused of planting armor-piercing roadside bombs in Sadr City and the adjacent Ubaydi area. U.S. forces used aircraft and an Abrams battle tank in Friday's attack, the military said. Iraqi health officials said about 75 people were wounded in those clashes.
U.S. soldiers killed four militants early Saturday elsewhere in Baghdad, the military said.
The American military also said Saturday that a U.S. soldier died of wounds sustained in a roadside bomb that struck the soldier's vehicle during a combat patrol in eastern Baghdad on Friday. The announcement came a day after the military said another roadside bomb attack in eastern Baghdad killed a U.S. soldier.
The fighting is part of a five-week-old crackdown by the Iraqi government and U.S. forces on Shiite militia factions. The clashes have brought deep rifts within Iraq's Shiite majority and pulled U.S. troops into difficult urban combat.
But Iraq's Prime Minister Nouri al-Maliki, a Shiite, shows no sign of easing the pressure on militia groups, including the powerful Mahdi Army.
Iraqi and U.S. forces are pressing deeper into Sadr City, and al-Maliki has been seeking to increase leverage on Iran, which is accused of training and arming some Shiite militias. Iran denies the claims.
A five-member Iraqi delegation went to Tehran this week to try to choke off suspected Iranian aid to militiamen.
Meanwhile, two civilians were killed and seven others wounded in Baghdad's central Salihiyah district Friday evening after a mortar round apparently fired by Shiite extremists toward the U.S.-protected Green Zone fell short.
Shiite militiamen have used Sadr City as a base to fire barrages of missiles and mortar rounds at the Green Zone, which houses the U.S. Embassy and much of the Iraqi government.