Honolulu police have opened an investigation into a fire at the Kailua home of the owner of the company that recently took over the Waikiki Beach concessions, although the Honolulu Fire Department is unable to determine the cause.

HFD said it received the fire alarm for a home on Iliaina Street at 6:08 p.m. Friday. When the first responders arrived a minute later they found the two-story house fully involved in flames.

Nine units and 34 HFD personnel responded to the alarm and got the flames under control by 6:26 p.m., and fully extinguished by 8:01 p.m. No one was injured in the fire.

Neighbor Joe Tvrdy, 72, who lives across the street, said the owner’s daughter was the only one home at the time of the blaze. “She grabbed the dogs and came out,” he said.

HFD fire investigators were at the home Saturday and estimated the fire’s damage at $800,000 to the structure and $400,000 to its contents. The investigators, however, were not able to determine the cause of the fire and closed the case after classifying the cause as undetermined.

HFD Capt. Carlton Yamada said the designation “undetermined” means the investigators analyzed all possible causes but found insufficient evidence to identify a specific cause. He said undetermined also means there was insufficient evidence to eliminate potential causes. He said the department can reopen the case if new information becomes available.

The Iliaina Street home belongs to Brian Benton, the owner of Dive Oahu Inc. The company became the vendor for two Waikiki Beach concessions after submitting the lowest bid to the city earlier this year.

Neither Benton nor his company manager responded to requests for comment.

Dive Oahu didn’t take over the concessions immediately after the city awarded the company two five-year contracts in April. One of the other previous vendors, Star-Beachboys Inc., sued to prevent the city from installing Dive Oahu. Star-Beachboys moved out in May after a state judge denied the previous vendor’s request for a temporary restraining order.

The other vendor, Hawaiian Ocean’s Waikiki, Inc., moved out later.

Tvrdy said he and his wife were having dinner at the back of the house when they heard a loud explosion, “a big boom.”

“We were worried about burning material, and worried for Brian,” he said.

Tvrdy said the windy conditions caused the fire to quickly sweep from one end of the house to the other, where there was a new addition that included a garage and upstairs ohana unit.

“By the time HFD arrived, half the house was in flames,” he said.

“Brian’s a good friend and a good neighbor,” he said.

Star-Advertiser reporter Leila Fujimori contributed to this report.