BAGHDAD — The killings of three U.S. soldiers in separate attacks in Baghdad pushed the American death toll for April up to 47, making it the deadliest month since September, the military said Wednesday.

One soldier died when his vehicle was struck by a roadside bomb. The other died of wounds sustained when he was attacked by small-arms fire, the military said. Both incidents occurred Tuesday in northwestern Baghdad.

A third soldier died in a roadside bombing Tuesday night in the east of the capital, the military said.

The statement did not give a more specific location. But the eastern half of Baghdad includes embattled Sadr City and other neighborhoods that have been the focus of intense combat between Shiite militants and U.S.-Iraqi troops for more than a month.

In all, at least 4,059 members of the U.S. military have died since the Iraq war started in March 2003, according to an Associated Press count.

"We have said all along that this will be a tough fight and there will be periods where we see these extremists, these criminal groups and al-Qaida terrorists seek to reassert themselves," U.S. military spokesman Maj. Gen. Kevin Bergner told reporters in Baghdad.

"So, the sacrifice of our troopers, the sacrifice of Iraqi forces and Iraqi citizens reflects this challenge," Bergner said in response to a question about what's behind the increase in American troop deaths.

The U.S. military said at least 10 gunmen had been killed in three separate clashes in eastern Baghdad late Tuesday and Wednesday.

The latest fighting erupted at the end of March after Prime Minister Nouri al-Maliki launched a crackdown against Shiite militias in the southern port city of Basra. But it quickly spread to Baghdad's Sadr City, a sprawling slum with about 2.5 million people that is a stronghold of the Mahdi Army militia of anti-American cleric Muqtada al-Sadr.

The militiamen have used the district as a base to fire barrages of missiles and mortar rounds at the U.S.-protected Green Zone which houses much of the Iraqi government and Western diplomatic missions, including the U.S. and British embassies.

They also have fought running street battles in which hundreds have died. The U.S. military says those killed have been mainly gunmen. But police and medical authorities in Sadr City say innocent civilians have frequently gotten caught up in the fighting.

Tahseen al-Sheikhly, the spokesman for the civilian side of Baghdad security operations, said Wednesday that a total of 925 people had died and 2,605 were wounded in Sadr City. But he gave no timeframe or details about how the figure was reached.

Previous Interior Ministry casualty figures for the past month had indicated that less than 400 people had perished. It was not immediately possible to reconcile the conflicting figures. Officials at the Baghdad military operations center said they could not confirm al-Sheikhly's count.

Also in Sadr City, AP Television News footage showed a school that had been badly damaged by an explosion on Tuesday. Parts of the two-floor building had pancaked as the result of the blast. Desks were hanging down from the slanting classrooms where the outer walls were blown out by the blast.

On Wednesday, al-Maliki accused the Mahdi Army of using civilians as human shields, and vowed to continue the crackdown against militias.

"We can't build a state along with militias," he told reporters at a news conference. "We want to build a single national army."

Al-Maliki said gunmen had killed the nephew of police Maj. Gen. Abdul-Karim Khalaf, an Interior Ministry spokesman who had also overseen operations in Basra, by hanging him from an electricity pole in Sadr City.

___

Associated Press writers Sinan Salaheddin and Qassim Abdul-Zahra contributed to this report.