U.S. soldiers killed 14 suspected Shiite militants in Baghdad, the military said Saturday, as clashes continued in the embattled Sadr City slum and surrounding militia strongholds.

A U.S. helicopter allegedly fired a missile Saturday at an apparent target about 50 yards away from Sadr City's general hospital, wounding about 28 people and damaging at least seven ambulances, hospital officials said.

The U.S. military did not have immediate comment on the alleged strike, but said in a statement 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, AP Television News footage showed. The explosion demolished a brick building and caused damage to several ambulances parked in front of the hospital, television footage showed.

U.S. and Iraqi forces have been locked in street battles with Shiite militias since late March in Sadr City, a slum of 2.5 million people and the base of anti-American Shiite cleric Muqtada al-Sadr's Mahdi Army.

The U.S. military said Saturday that 10 militants were killed in fighting on Friday, including a sniper and a triggerman accused of staging 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 announced 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 comes a day after the military said another roadside bomb attack in eastern Baghdad killed a U.S. soldier.

As clashes escalate in Sadr City, Shiite clerics have offered sharply different visions in the showdown between government forces and Shiite militias. One cleric predicted Friday that armed groups will be crushed in Baghdad, and another called for Iraq's prime minister to be prosecuted for crimes against his people.

The contrasting views showed the complexities and risks in the 5-week-old crackdown by the Iraqi government and U.S. forces on Shiite militia factions. The clashes have brought deep rifts among Iraq's Shiite majority and have pulled U.S. troops into difficult urban combat.

But Iraq's Prime Minister Nouri al-Maliki, a Shiite, shows no indication of easing the pressure on militia groups, including the powerful Mahdi Army led by anti-American cleric Muqtada al-Sadr.

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 militia groups. Iran denies the claims.

A five-member Iraqi delegation was sent 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.