Mourners believed smoke billowing from a Sydney crematorium was normal -- until they were asked to evacuate the building because of a fire in the roof.
About 80 people, some attending a memorial service, fled the crematorium at Rookwood Cemetery just after 10am today.
Fire crews have the blaze under control, but are still putting out spot fires.
A fire brigade spokesman said the roof of the building had collapsed inward.
He said six crews had worked to contain the blaze.
"There is substantial damage," he said.
"Crews will be mopping up for a while yet."
One of the mourners, Mary Ide, said a man had interrupted the service she was attending and told everyone to evacuate.
"We could see smoke at the windows coming out," she told the ABC.
"We thought it was the other side of the crematorium cremating somebody but the smoke got darker and darker and we (could) see action going on outside."
The cause of the fire had yet to be determined.
No injuries were reported.
