Honolulu police have opened a first-degree arson investigation in connection with Wednesday night’s fire that destroyed a 43-foot fishing boat at the Ala Wai Boat Harbor.

Police said an unknown suspect set the boat on fire just before 8:40 p.m.

More than 40 firefighters responded to the fire at slip 520. Upon arrival, crews saw the vessel engulfed in flames, Honolulu Fire Department officals said.

There was no one on the boat at the time of the fire.

Firefighters brought the fire under control shortly after 8:50 p.m. and extinguished it by about 9 p.m.

No injuries were reported.

Damage to the vessel was estimated at $600,000, according to police. Heat from the flames also caused exterior damage to a nearby boat.

Police had made no arrests as of this morning