Insurgents fired at least seven rockets on the U.S. coalition headquarters in Baghdad (search) Sunday night, hitting a hotel used by U.S. occupation officials and wounding one American, the military said. It was the biggest attack on the Green Zone (search) in weeks.

A series of explosions echoed across central Baghdad from the strike, sirens blared, and smoke and flames were briefly visible in the Green Zone, the heavily guarded area where the U.S.-led coalition is based.

Five rockets hit the Al-Rasheed hotel (search), where some civilian contractors are living and a coalition dining hall is located. A U.S. civilian contractor was wounded, the military said.

The rockets were fired around 7:30 p.m. from a white SUV parked outside the Green Zone near the former Foreign Ministry building. The SUV burst into flames during the barrage, and U.S. troops found two rockets in a rack on the vehicle. The troops then blew up the vehicle, a military spokesman said.

The Al-Rasheed is located across the street from the Baghdad Convention Center (search), where many coalition offices are located. The center was where Iraq's Governing Council (search) intended to sign an interim constitution on Friday, but a last-minute political dispute delayed the ceremony. Council members said they hoped to sign the document Monday.

Earlier Sunday, some 500 U.S. soldiers, backed by tanks and helicopters, raided Baghdad's biggest dairy processing plant, in the western suburbs of the capital, looking for specific militant suspects. Four people were arrested, battalion commander Lt. Col. Tim Ryan told The Associated Press.

Troops entered the grounds of the eight-building plant without incident and checked identity papers of the workers, separating men and women.

After the raid, soldiers handed out Arabic-language newspapers printed by the coalition, and handbills offering rewards for information about suspected militants or bomb makers.

The Green Zone comes under occasional mortar or rocket fire, but Sunday night's barrage was the biggest attack in weeks.

Inside the Green Zone, employees at the Baghdad Convention Center, where the U.S. military press office is based, fled into the basement, said Army 1st Sgt. Stephen Valley, a military spokesman.

"Everyone's OK. Everyone's been accounted for," Valley said. "They're all down in the basement."

Shortly after the blasts, a U.S. Army OH-58 Kiowa helicopter, a surveillance aircraft, and an Apache helicopter flew low over the nearby Tigris River, possibly in an attempt to seek out the heat signature of the rocket launchers. The helicopters use infrared sights to seek out the heat left by the rocket tubes.

The Green Zone was last struck on March 3, when a U.S. Army spokesman confirmed that a rocket hit the area. No one was injured and no damage was reported.

"I heard the blasts at about 7:40. There was a fire glow and then a lot of smoke," said Iraqi Ali Shawqi, who stood about 100 meters (yards) from the scene of the blasts when they happened.

In northern Iraq, insurgents fired a rocket-propelled grenade at a police station in the city of Mosul in a drive-by attack that killed two Iraqi civilians and wounded two police officers, police said.