BAGHDAD (AP) - Seven American soldiers were killed in southern Iraq early Thursday when their Chinook helicopter crashed as it was flying into the country from Kuwait, the U.S. military said.

The military said the helicopter did not come under attack, and that even though the cause of the crash is still undetermined, it was certainly an accident.

"At this time we are uncertain of the cause, but hostile fire has been ruled out," military spokesman Maj. John Hall said. "The other three helicopters in the flight did not have incident or injury."

Hall said that seven Americans died.

The CH-47 Chinook crashed shortly after midnight in the desert about 60 miles (96 kilometers) west of Basra, the military said.

The chopper was a part of an aerial convoy flying from Kuwait to the U.S. military base at Balad north of Baghdad. The Chinook, the Army’s workhorse, is designed to transport troops and supplies to combat and other regions.

On Wednesday, gunmen killed a Sunni assistant to the governor of one of Iraq’s most volatile provinces, the latest in a series of attacks that have marred the Islamic holy month of Ramadan.

Shamil Younis, an engineer who handled technical affairs for Gov. Duraid Kashmola, was killed in a drive-by shooting as he was walking home after finishing prayers at a nearby mosque in Mosul, police said. The attack occurred shortly after iftar, the meal that breaks the sunrise-to-sunset fast during Ramadan.

The governor, also a Sunni, confirmed the slaying and promised an investigation. He called it "a brutal crime against this innocent, good man."

Kashmola, who is the governor of Ninevah province of which Mosul is the capital, himself survived an apparent assassination attempt this summer.

The June 26 car bombing struck near the site where Kashmola was inspecting damage from an earlier explosion that police believed was meant to lure him to the market area in Mosul. At least 18 people were killed in the attack.

Nobody claimed responsibility for the killing of Younis, but it comes as insurgents - most of them Sunnis - are making a stand in Mosul, 22 miles (360 kilometers) northwest of Baghdad, after being routed in Baghdad and other urban centers.