KIHEI, Maui — Fire and police officials were investigating an early-morning fire that gutted a senior center under construction at the Hale Mahaolu Ehiku complex on Wednesday, causing an estimated $1.5 million in damage.

Responding to the 5:45 a.m. alarm at the complex at 64 Ehiku St., off Welakahao Road, firefighters were on scene within seven minutes, said acting fire Battalion Chief Sheldon Holokai.

"It was fully involved," said Holokai, who responded along with crews from Kíhei, Kahului and Wailea, as well as fire prevention, health and safety, and hazardous materials units.

About 25 firefighters fought the blaze, bringing it under control at 6:58 a.m.

Holokai said the main portion of the 4,500-square-foot, unoccupied building was engulfed in flames, which spread to the roof of a smaller, connected part of the building.

Officials said damage was estimated at $1.4 million to the building and $100,000 to its contents. The cause was undetermined.

Roy Katsuda, executive director of Hale Mahaolu, said the building that burned was a senior center and included a commercial kitchen. He said the adjoining area, separated by a breezeway, had space for a laundromat, meeting and conference rooms, and a dental office. It was part of the second phase of the four-phase project designed to include housing as well as space for other agencies and eventually a care home.

"This is our most comprehensive 'aging-in-place facility,' " Katsuda said.

The burned building was about 90 percent finished and about two months away from completion, he said, with mostly interior work remaining. The building was in an area surrounded by orange construction fencing.

At the scene Wednesday morning, Katsuda said an adult day care center next to the building that burned looks intact. Twenty-one unoccupied housing units nearby also were not damaged by the fire, he said.

While the fire was a setback, "everybody recognizes it could have been worse," Katsuda said. "Nobody was hurt."

Before the fire was reported, a resident of the occupied 34-unit Hale Mahaolu apartment building said she saw what looked like the flicker of a small flashlight or penlight at the nearby construction site.

"The light was moving back and forth, back and forth, and then all of a sudden, I saw smoke," said Maria Pola, whose second-floor apartment terrace faces the building that burned.

She said the spot of light was flickering from between the two sections of the senior center building while it was still dark and about an hour before construction workers usually arrive at the site.

She didn't think anything was amiss until she heard a "whoosh" that sounded like water flowing and shattering glass. She went outside in her pajamas to move her car, which was parked between her apartment and the building.

No more than 10 minutes later, "When I got back, the building was in flames," she said. "The flames were shooting out of the building."

She called the building manager, who called 911.

Kaitee Lusk, who could see the fire from the landing of her third-floor apartment at Hale Mahaolu, said the wind direction kept the fire from spreading to the occupied apartments.

"It was pretty scary," she said. "The flames were huge, just huge. The fire department responded really quickly. I just thank the Lord they did."