WAIAU — Fire officials were investigating the cause of a fire in Waiau Center that destroyed two businesses and severely damaged another early yesterday morning.

Firefighters responded at 1:38 a.m. to a call of at least one loud "boom" and flames shooting 40 feet high from the roof of Ocean Fresh Seafood and The Hawaiian Chef, both at the 'ewa end of the strip mall.

They had "significant damage," said Honolulu Fire Department spokesman Capt. Terry Seelig. "You can say they were destroyed."

Pat's Island Delights also was damaged but was probably repairable, he said.

Approximately 20 patrons and workers at Zippy's, which fronts the center, were forced to evacuate. Police also went to nearby neighborhoods, waking residents and initially asking them to evacuate.

"They were knocking on doors, basically," said Gerald Lau, who lives in the neighborhood behind the center, about 500 yards away. "They said they thought there was a chance there was chlorine or some sort of chemical at first, but then they came back and said we could stay. They were worried about the propane tanks nearby."

Ten engines and two ladders, encompassing 40 firefighters, responded to the call, Seelig said. The fire was deemed under control at 3:15 a.m., but firefighters continued to look for pockets where the fire could flare up until 4 a.m.

"We had reports of an explosion inside, and we had propane tanks outside," Seelig said. "We had to use defensive tactics to fight this one — rather than go inside, we had to shoot water from the outside, so it took longer to get under control."

The investigation was slower because the amount of destruction to the building made it unsafe, Seelig said. Crews removed the roof yesterday, creating a heap of charred beams and wood.

"They're using some equipment to pull the roof off so they can work underneath it where the fire burned," Seelig said. "We're basically just rendering it safe to be able to conduct the investigation."

The strip mall, which is owned by Zippy's Restaurants, has about 10 tenants, including Love's Bakery Thrift Store and Wholesale Unlimited Express.

The strip mall tenants were without power yesterday, and some left their doors open to clear out strong smoke odors.

The Love's Bakery Thrift Store had some water and smoke damage and would be dumping the food stored there, said manager Sharon Samson. She estimated they will reopen in about two weeks, which would result in a loss of up to $5,000 in sales.

Still, the damage is minor compared with the other businesses, she said.

Yates Honma, president of Wholesale Unlimited Express, went to the site at 6 a.m. and was relieved that his store was intact, "but we also felt bad for the stores that did get damaged."

He planned to reopen when the power was restored. He said a health inspector told him the food would be safe so long as it's sealed, but Honma said he's going to test the products anyway.

"It was a shock, but all things considered, we do consider ourselves very lucky ... especially for the fact that no one got hurt," he said. "That's the main thing."

Jean Santiago, owner of Rejuvenation Skin Care Salon LLC, was assessing whether the smoke may have damaged her products or equipment. She hopes to reopen the business by the weekend.

"I'm not sure how much damage I really do have," she said. "I took all the stuff off my shelves because I want to test them to see if they're usable. ... Fortunately for us, the middle of the week is slow. It will give us a few days to get ourselves together in hopes that we can be open for the weekend."

Reach Dave Dondoneau at ddondoneau@honoluluadvertiser.com and Lynda Arakawa at larakawa@honoluluadvertiser.com.