A man who opened fire on a church with an AR-15 was suffering a mental breakdown and attended the congregation with his mother.

Brian Browning, 31, was shot dead by security guards at CrossPointe Church in Wayne a suburb of Detriot, on Sunday morning.

He began the attack by ramming his Ford F-150 truck into the building at 11.06am before he opened fire during service.

The Wayne Police Department said he 'may have been suffering a mental health crisis' and had nothing to do with organized terrorism.

'The suspect’s mother is a member of the church, in which he has attended church services two or three times over the course of the last year,' it said.