BAGHDAD — Bombardments by suspected militants killed four U.S. soldiers Monday as troops tried to push Shiite fighters farther from the U.S.-protected Green Zone and out of range of their rockets and mortars.

At least 44 American soldiers have been killed in Iraq in April, making it the deadliest month for U.S. forces since September.

The U.S. military said three soldiers were killed in eastern Baghdad by indirect fire, a reference to mortars or rockets. The statement did not give an exact location for the attack, but the Shiite stronghold of Sadr City has been the scene of intense fighting recently with Shiite militiamen.

A fourth U.S. soldier was killed by a shell in western Baghdad, the military said.

A showdown between the Iraqi government and the Mahdi Army — led by anti-American cleric Muqtada al-Sadr — has increasingly drawn U.S. forces into battles.

OUTSIDE GARMSER, Afghanistan — U.S. Marines exchanged gunfire with militants today after pouring into a Taliban-held town in southern Afghanistan in the first major American operation in the region in years.Several hundred Marines, many of them veterans of the conflict in Iraq, pushed into Garmser in pre-dawn light in an operation to drive out the insurgents, stretching NATO's presence into an area littered with opium poppy fields and classified as Taliban territory.U.S. commanders say Taliban fighters were expecting an assault and planted homemade bombs in response. The British have a small base on the town's edge but Garmser's main marketplace is closed because of the Taliban threat.Marines moved into town by helicopter and Humvee for Tuesday's assault in Helmand, the first major task undertaken by the 2,300 Marines in the 24th Marine Expeditionary Unit, which arrived last month from Camp Lejeune, N.C. for a seven-month deployment. Another 1,200 Marines arrived to train Afghan police.British troops — who are responsible for Helmand — have faced fierce battles on the north end of Helmand.

AMSTETTEN, Austria — Police today inspected properties owned by the man they say confessed to imprisoning his daughter for 24 years and fathering her seven children to make sure he did not have any other underground cells for holding captives.Investigators believe it is "more than unlikely" that Josef Fritzl maintained other secret prisons but police were checking as a precaution.Police said the 73-year-old confessed to imprisoning his daughter Elisabeth, now 42, sexually abusing her, fathering her children and tossing the body of one child who died in infancy into a furnace.Investigators say they believe Fritzl's wife was unaware that the daughter she believed ran away in 1984 was living as a prisoner beneath her feet. Three of Elisabeth's surviving children lived with the grandparents and were registered with authorities while the other three never saw sunlight for years until being, authorities said.