No one was injured when a Toronto streetcar caught fire on Wednesday morning but police say a section of King St. East was blocked for three hours.

The 504 King streetcar, travelling westbound on King Street East at Sumach Street, was evacuated safely after overhead wires fell onto the roof sparking a fire, said Brad Ross, spokesperson for the TTC. 

There were 12 passengers on board.

"The overhead wires did come onto the roof. The wires may have fallen and touched the ground," Ross said. "We don't know why they came down. It may have been due to the car before."

Ross said power was cut to the streetcar and the TTC diverted the westbound 501 Queen and 504 King streetcars for less than an hour as crews removed the vehicle and repaired the wires.

"These cars are 35 years old in some cases and they are beyond their operational life. This may be one of those cars," he said. "We'll have to have a look at it."

Captain Adrian Ratushniak, spokesperson for Toronto Fire Services, said a bystander reported flames coming from the roof of the streetcar shortly after 10 a.m. He said it was stopped and the passengers were able to get out. The fire is under investigation and there is no word yet on the cause.

Const. Victor Kwong, spokesperson for Toronto police, said there was smoke but no report of injuries. He said a section of King Street East, westbound near Richmond Street East, was blocked for three hours.

"It wasn't an engulfed fire. By the time we got there, everybody was out," he said.

A video posted to YouTube shows small flames under the streetcar and part of the roof blackened.