Insurgents fired a rocket at U.S. troops in western Iraq, killing two soldiers, while in Baghdad (search), rockets fired toward the U.S.-led coalition headquarters Sunday killed two Iraqi civilians and injured an American soldier.

The attacks came a day after the first anniversary of the start of the war that ousted Saddam Hussein (search).

A 1st Infantry Division soldier was also killed Sunday in an apparent accident during a weapons firing exercise in Samarra (search), about 60 miles north of Baghdad, Army spokeswoman Maj. Debra Stewart said. The incident was under investigation.

One of three rockets fired in Baghdad landed inside the coalition headquarters but caused no significant damage, a U.S. official said, speaking on condition of anonymity. The wounded soldier was hit by flying glass. Staff and journalists in the compound were instructed to take cover inside a bunker.

Two rockets landed outside the compound in the upscale neighborhood of Mansour (search), killing two Iraqi civilians and wounding five, the official said. However, officials at the nearby Yarmouk Hospital said one person died and 10 were wounded. Residents said the rockets landed in a street, damaging several cars and shops.

"This is a terrorist act. There are no military targets in Mansour," said Raed Abdul Saheb, a doctor at the hospital.

Mortar and rocket attacks on the coalition headquarters are common. The assaults often miss and hit nearby neighborhoods.

The rocket attack in western Iraq occurred Saturday evening near the city of Fallujah, where anti-U.S. rebels are active, the official said. Five soldiers and a sailor were also wounded, besides the two soldiers killed, she said. No other details were available.

In the northern city of Kirkuk, unidentified gunmen inside an ethnic Turkman youth center fired at Kurds waving flags to celebrate the Kurdish new year, killing one and wounding four others on Sunday, said Abdul-Salam Zangana, a security official at a hospital.

The millions of Iraqis who exulted in Saddam's downfall did not publicly celebrate the first anniversary of the start of the war, nor were there street protests from those who enjoyed his patronage — partly because public gatherings are vulnerable to suicide attackers, car bombs, shootings and other violence.

Even those who opposed Saddam are uncomfortable with the invasion and extended occupation of Iraq by foreign armies.

Many Iraqis fear daily they will be caught in the crossfire of the conflict between U.S. forces and anti-American insurgents and other shadowy assailants; some said they felt more insecure now than they did before the United States launched military strikes.

Hours after U.S. Marines officially took control Saturday from the 82nd Airborne Division of a swath of territory west of Baghdad, the U.S. military said rebels had killed a U.S. Marine in the area, Anbar province, a day earlier. Two Marines also died in combat Wednesday in Anbar, which includes parts of the so-called Sunni Triangle where guerrilla attacks have been fierce.

At the handover ceremony at a U.S. base in Ramadi, Marine commander Maj. Gen. James Mattis issued a warning to insurgents.

"We expect to be the best friends to Iraqis who are trying to put their country back together. And for those who want to fight, for the foreign fighters and former regime people, they'll regret it. We're going to handle them very roughly," he said.

Thousands of war protesters marched in Asian, American and European cities on the first anniversary of the invasion, demanding the withdrawal of U.S.-led troops from Iraq.