GRAND BLANC TOWNSHIP, MI – As local and federal authorities continue to try to grasp what motivated a man to barrel into a Michigan church Sunday morning, spraying bullets and lighting it on fire in a deadly attack, some pieces of the man’s background are becoming more clear.

Law enforcement identified Thomas Jacob Sanford, 40, of Burton, as the man who rammed a four-door pickup into the Church of Jesus Christ of Latter-day Saints in Grand Blanc Township on Sunday morning.

The FBI is now leading the investigation and described Sanford’s actions as “targeted violence” that left four dead, eight injured, and possibly others unaccounted for in the burned-out church.

The pickup Sanford used to ram into the church had two American flags planted in the truck’s back bed area. After using an assault rifle to open fire on people who had gathered for the service, Sanford is believed to have used gas to start the church on fire, police said.

The ATF said the shooter also had explosive devices with him, but they were still trying to determine if he’d used them.

According to The Associated Press and The Detroit News, Sanford served in the Marines for four years, from June 2004 through June 2008. He worked as a mechanic.

His enlistment included a deployment to Iraq from August 2007 through March 2008. He had the rank of sergeant. He later worked as a truck driver.

After Sunday’s attack, the Michigan State Police Bomb Squad and other law enforcement arrived to search Sanford’s Burton home. Authorities have not said what they found there.

They also have not said if he was a member of The Church of Jesus Christ of Latter-day Saints, widely known as the Mormon church.

Reached by phone, Sanford’s father declined to discuss his son.