The fire at the Universal Church at 3541 20th St. was reported at 2:45 p.m., according to the fire department.
A second alarm was called shortly before 3 p.m.
Firefighters contained the fire about an hour later but as of 4:10 p.m. had not yet declared it fully under control, fire spokeswoman Mindy Talmadge said.
A crew was working on the roof when the fire broke out but all the workers got off safely and no one was injured, she said.
Fire investigators are responding to determine the cause of the fire, Talmadge said.