A suspicious fire in a restroom shut down a fast-food restaurant Thursday night.

Suffolk Fire and Rescue responded to the fire at the McDonald’s restaurant at 601 N. Main St. around 8:24 p.m., according to a press release from city spokeswoman Diana Klink.

Three engines and two ladder trucks responded to the fire, which was quickly brought under control, according to the release. There was minimal damage in the restroom, but the restaurant was evacuated because of heavy smoke.

It remained closed Thursday night. It was not immediately clear when it would reopen, and nobody answered the phone at the restaurant.

No injuries were reported. The Suffolk Fire Marshal’s Office is investigating the cause of the fire.