CHARLESTON, W.Va. — An Iraq war veteran suspected of killing his former girlfriend and her pregnant sister in Michigan fatally shot himself in a remote West Virginia cabin after seeing investigators closing in, authorities said Wednesday.

Deputy marshals and Tyler County sheriff’s deputies were approaching the cabin near Sistersville on Tuesday evening when they saw Thomas Fritz run inside holding a rifle, said Alex Neville, a deputy marshal in Clarksburg. Seconds later, they heard a gunshot.

Not knowing whether Fritz, 38, had shot himself or fired on them, the investigators requested help from special units from Wetzel County and the State Police, Neville said.

Officers fired tear gas into the cabin and stormed in. They found Fritz dead of a self-inflicted gunshot wound in a rear bedroom, along with two assault rifles, a shotgun, and a gas mask, Neville said.

Authorities warned after the Friday killings that they considered Fritz armed and dangerous. Fritz served in the Ohio National Guard in 1997 and later the Army Reserve. He then spent nearly a year in Iraq with the guard’s military police unit from the spring of 2003 through early 2004.

Fritz had once worked for the man who owns the cabin, which is in a remote area near the Ohio border about 80 miles southwest of Pittsburgh, Pa., Neville said.

Authorities said Fritz’s ex-girlfriend, Amy Merrill, broke up with him about three weeks ago. On the night of the killings, he went to her Blissfield, Mich., home to speak with her. The two had a child together, and Merrill’s two sons from a previous marriage lived there.

Police say Fritz shot Merrill, 33; her sister, Lisa Gritzmaker, 24, who was eight months’ pregnant; and their mother, Robin Lynn McCowan, who were all at the home. McCowan is recovering at a hospital.