A blaze that broke out in the Sunday school rooms of a church in San Francisco Sunday morning caused extensive damage to that area, according to the church's pastor and fire officials.

The fire, which ignited before services at Christ Church Lutheran ELCA located at 1090 Quintara St., has been deemed suspicious and may have been intentionally set, according to fire officials and Pastor Steven Sabin.

Sabin said his associate pastor arrived at the church around 8:30 a.m. and noticed a smoky smell inside. Arriving firefighters found that a fire ignited in the church's basement where the Sunday school rooms are located.

Sabin added that the fire department is conducting an arson investigation.

"They said that there were accelerant marks on the floor and it looked like the fire had been intentionally set," Sabin said.

Sabin was not sure who may have possibly started the fire, but he did note that the church has had "a little bit of trouble with people being in the church without permission."

No one was injured in the fire, according to Sabin.

There was some smoke damage but no structural damage to the level above the Sunday school rooms, Sabin said.

Church services were not affected as a result of the fire, fire officials said.

An investigation into the fire is ongoing.