The woman went to the World Islamic Mission's mosque on Tuesday and asked to use its toilet. Video from the facility's surveillance cameras show that she set fire to a paper towel that she brought with her out of the restroom, Aftenposten reported.
While she attempted to use the paper towel to start a larger fire, 15 people were praying one floor above her.
Those praying were able to extinguish the fire.
The World Islamic Mission has up until now been open to anyone who wants to look around or use the facility to pray. School groups have also been welcome. But now, management said it will reconsider both the mosque's safety measures and opening hours.
“Arson creates fear amongst the Muslims in Oslo,” Mehtab Afsar of the Islamic Council of Norway said.
The arson attempt was reported to police and is currently being investigated.