HARRIS COUNTY, Texas -

Fire investigators are trying to determine the cause of a massive two-alarm fire that destroyed a former nightclub in northwest Harris County.

The Ponderosa Fire Department was called to a vacant building in the 14700 block of Kuykendahl just before 9 a.m. Sunday. The fire at the former Club Bugatti was so intense that firefighters eventually called for a second alarm.

“We have in the neighborhood of 75 firefighters and multiple apparatus from several fire departments in north Harris County,” said Chief Fred Windisch with the Ponderosa Fire Department.

Lieutenant Dean Hensley with the Harris County Fire Marshal's Office said it took firefighters about three hours to put out the flames and two firefighters were treated at the scene for heat exhaustion.

The owner of the building told fire investigators the club closed about a year ago and he was in the process of getting new tenants. Hensley said the fire is considered suspicious because there was no electricity to the building and a door appeared to have been tampered with.

“They did find what appears to be a forced entry, or an open door at the front of the building. We're looking at that also,” said Hensley.

Hensley said the building is considered a total loss.