Four people were killed and several others wounded Sunday when authorities say a man opened fire at a Church of Jesus Christ of Latter-day Saints in Grand Blanc Township, Michigan, and set it ablaze in what a federal official called “an act of targeted violence.”

At least two of the four victims were fatally shot, police said. Eight people were wounded, with one in critical condition and seven who were stabilized, township Police Chief Bill Renye said.

Authorities were searching through the debris of the church for anyone who might be unaccounted for.

The suspect, Thomas Jacob Sanford, a 40-year-old former Marine, was killed by law enforcement.

Here is what we know about the shooting.

Follow live updates

How the attack unfolded

At 10:25 a.m. Sunday, a gunman drove a vehicle into the church, got out and opened fire with an assault rifle, Renye said.

The first officers arrived within 30 seconds of initial reports, and law enforcement killed the shooter in the church’s rear parking lot 8 minutes after the first reports, he said.

Authorities believe the shooter was able to spark a fire that eventually enveloped the church before it was contained, Renye said.

Paula Maser was among the worshippers in the church for a Sunday service.

“We heard a big bang and it blew the doors in the church, and then everything after that was chaos,” Maser told NBC affiliate WEYI of Clio, Michigan.

Maser said she and others ran outside, where she and a friend got into a car. The gunman also went outside, Maser said, and continued to fire. Three bullets struck the car Maser was in, she said, one of which grazed her friend’s hand.

Janet Peera, who lives nearby, told the news station that she and her family were leaving their home when they saw police vehicles and fire trucks racing toward the scene and heard gunshots.

Amid the chaos, Peera said, the family ended up in the church parking lot.

“There were bodies lying on the sidewalk,” she said. “There was one lying in the back of somebody’s truck that had just gotten shot maybe a couple times in the leg.”

Where the investigation stands

It’s not clear what motivated the shooting, and officials did not disclose whether there was any known connection between the suspect and the church.

The FBI is investigating the incident as “an act of targeted violence,” Reuben Coleman, the acting special agent in charge of the bureau’s Detroit field office, said during a news conference Sunday night.

“This act of violence has no place in our state or anywhere else in our country,” Coleman said. “The FBI is committed to continue finding out the facts, circumstances and motives behind this tragedy.”

The Bureau of Alcohol, Tobacco, Firearms and Explosives is also aiding in the investigation. James Deir, special agent in charge of the ATF’s Detroit Field Division, said the investigation indicates an accelerant, believed to be gasoline, was used by the suspect to set the blaze. He also said “suspected explosive devices” were found at the site, but it’s not clear if those sparked the inferno.

Renye said the church is a “total loss” as a result of the fire, and there are some people still unaccounted for.

None of the victims had been identified as of Sunday night, and officials said first responders are in “recovery mode,” sifting through debris from the blaze for additional bodies and evidence.

What we know about the suspect

Sanford, of Burton — a city roughly 6 miles from Grand Blanc Township — has a military background.

Sanford joined the Marine Corps in 2004 and held the titles of organizational automotive mechanic and vehicle recovery operator during his time in the service, according to corps records.

His service included a deployment from August 2007 to March 2008 under Operation Iraqi Freedom, according to the corps.

He had become a sergeant and had his last duty assignment at Camp Lejeune in North Carolina, according to the corps. He left the military in June 2008, according to the records.

Awards for his service include the Marine Corps Good Conduct Medal, Sea Service Deployment Ribbon, Iraq Campaign Medal, Global War on Terrorism Service Medal and National Defense Service Medal, the records show.

A 2007 story in the Clarkston News said Sanford graduated in 2003 from nearby Goodrich High School. Goodrich Area Schools officials did not immediately respond to a request to confirm that reporting. The publication said he was soon to be deployed to Fallujah, Iraq.

Attempts to reach multiple family members were unsuccessful Sunday.