At least four people have been killed and eight others injured after a gunman drove a vehicle into a Michigan church, opened fire and set the building ablaze, police say.

Officials said the attack on the Church of Jesus Christ of Latter-day Saints in Grand Blanc, a town 60 miles (100km) northwest of Detroit, happened during a Sunday service attended by hundreds of people.

The suspect, identified as Thomas Jacob Sanford, 40, from Burton, Michigan, was later shot dead by police in the church car park.

Authorities are investigating the incident as an "act of targeted violence", but say the motive remains unclear.

Two victims died from gunshot wounds, Grand Blanc Township Police Chief William Renye told a news conference on Sunday.

He later said two more people had been found dead and "some" others remained unaccounted for, though he could not say how many. The church was still being "cleared" on Sunday night after suffering extensive fire damage, he said.

Chief Renye said "hundreds" of people were attending services at about 10:25 local time (15:25 GMT) when a gunman drove a vehicle into the building.

The attacker then opened fire with an assault-style rifle, "firing several rounds at individuals within the church," he said.

The police responded immediately to the scene, he said, adding officers "engaged in gunfire with that particular individual, neutralising that suspect". Sanford was killed at 10:33 local time, eight minutes after the shooting.

"We are still trying to determine exactly when and where the fire ended up coming from and how it got started," the police chief said.

The suspect had used an accelerant - most likely gasoline - to start the blaze, authorities said.

Chief Renye also praised the "heroism" of churchgoers who he said had sheltered children in the church during the incident.At least four people have been killed and eight others injured after a gunman drove a vehicle into a Michigan church, opened fire and set the building ablaze, police say.