Baghdad ? The U.S. military death toll hit a seven-month high of 50 on Wednesday – with more than half the losses in Baghdad as American forces wage growing street battles against Shiite fighters.

Iraqi civilian deaths also remained high following the Iraqi government crackdown on Shiite militia factions – accused by Prime Minister Nouri al-Maliki of using residents as human shields during close combat in the teeming Sadr City slum.

The clashes in Sadr City – a base for the powerful Mahdi Army militia – show little sign of easing as Iraqi and U.S. troops try to exert control over an area containing nearly half of the Baghdad’s population.

In the deadliest skirmish Wednesday, suspected Shiite extremists first attacked with mortars and machine guns, then drove up a U.S. checkpoint and opened fire. The U.S. military said seven militants were killed. At least 10 other militiamen died in other clashes, the military said.

But the growing violence in Baghdad also has taken a toll on U.S. forces.

At least five soldiers have been killed in the city since Tuesday, bringing the monthly count to at least 50 – 27 in Baghdad – in the deadliest month since September when 65 U.S. troops died.

Since the U.S.-led invasion in 2003, at least 4,062 U.S. military personnel have died in Iraq, according to an Associated Press count.

The U.S. military reported early Thursday that a soldier had been killed by an explosion Wednesday near a patrol in Ninevah Province.

Around Iraq, at least 1,080 Iraqi civilians and security forces were killed nationwide this month, or an average of 36 a day, according to an AP tally. That’s down from March’s total of 1,269, or an average of 41 per day.

But nearly 40 percent of the April deaths – 413 – occurred in Baghdad as violence returned to the capital, according to the AP figures compiled from reports from Iraqi police, hospital officials and government offices.

Civilian deaths have steadily risen this year, and spiked sharply after al-Maliki launched the offensive on Shiite militias on March 25 in the southern city of Basra. Fighting soon flared in Sadr City, which has become the epicenter of the battles.