OKLAHOMA CITY—Four Texans and three Oklahomans were among seven National Guardsmen killed early Thursday in a helicopter crash in southern Iraq, an aide to U.S. Rep. Mary Fallin confirmed.

The soldiers were members of the Texas National Guard and Oklahoma National Guard, said Alex Weintz, press secretary for Fallin, R-Okla.

Statements released Thursday afternoon by the Oklahoma National Guard and Gov. Brad Henry said three Oklahoma Guard members were believed to have been among the fatalities.

“It is believed that three of the casualties were Oklahoma Guardsmen from Detachment 1, Company B, 2nd Battalion, 149th Aviation from Lexington, Okla.,” according to the National Guard statement.

Maj. Gen. Harry M. Wyatt III, adjutant general of Oklahoma, said the unit is made up of about 200 Oklahoma and Texas guard members. It was mobilized in June and left for duty in Iraq in late August.

“Today we mourn the loss of three Oklahomans who made the ultimate sacrifice,” Henry said. “They were courageous men of duty and honor, and our thoughts and prayers are with their families and loved ones during this challenging time.”

The military did not release the names or hometowns of those killed pending notification of next of kin.

The deaths of the three Oklahoma soldiers bring to 70 the number of Oklahomans killed in Iraq since 2003.

The CH-47 Chinook was flying in a four-helicopter formation from Kuwait to the U.S. military base at Balad, north of Baghdad, when it crashed shortly after midnight in the desert about 60 miles west of Basra, the military said.

In Washington, a Pentagon official said officials suspect a malfunction on the Chinook.

“They think it was a mechanical problem,” he said on condition of anonymity because he was not authorized to speak to the press on the record.

Earlier, a military spokesman in Baghdad, Maj. John Hall, said hostile fire had been ruled out.

“The other three helicopters in the flight did not have incident or injury,” Hall said.