Crews worked Tuesday to clear debris from the hull of a burned church, charred in Sunday's attack that left four people dead and eight others wounded.

The attack occurred just as services were underway in the crowded sanctuary. Authorities feared they would find additional victims, but by Monday everyone was accounted for after a sweep of the charred ruins, police said.

Investigators were focusing on what motivated a 40-year-old veteran to open fire and set ablaze the church in Grand Blanc Township, about 60 miles (96 kilometers) north of Detroit. The suspect was also killed while exchanging gunfire with two officers, said Township Chief of Police William Renye.