A fire broke out outside a popular Pioneer Square nightclub early Monday morning and fire officials are investigating the fire’s cause as a possible arson.

The fire broke out around 3 a.m. at the Trinity nightclub in the 100 block of Occidental Ave. South, according to Seattle Fire officials.

Investigators say most of the fire damage was outside the front door and in a vacant part of the club. Luckily the building’s sprinkler system activated and helped prevent the spread of flames.

Firefighters arrived moment later and finished dousing the fire. No one was hurt.

Investigators are still looking into how the fire started but have described the fire as “suspicious.”