Several church members were working on the gabled roof on Tuesday evening when an interior wall caved in, burying the two victims around 7 pm, police said. The 49-year-old priest and an unidentified 36-year-old man both died on the scene.
Five other people at the Westend neighbourhood church suffered from shock and were treated in a nearby hospital, police reported.
Some 60 rescue workers closed Heerstraße for clean up and to investigate how the roof could have collapsed. Officers speculated that it probably occurred due to the renovations undertaken by church organisers.
About 40 officers from the State Office of Criminal Investigation (LKA) are looking into the incident.