The City Council’s upcoming debate on a fireworks ban will be under more intense scrutiny as fire officials reported yesterday that an illegal, professional-grade aerial set off a wildfire that burned 200 acres in Kalama Valley and forced the evacuation of dozens of residents.

The Fourth of July blaze threatened homes worth $50 million, officials said.

Kamehame Ridge resident Jo Ann Viernes was packed and ready to evacuate ahead of the flames Sunday night. The order never came.

But her relief turned to anger at the Honolulu Fire Department’s revelation yesterday that the fire was started by illegal pyrotechnics.

"I’m furious," Viernes said. "I’m really, really upset. Those poor firemen have been working nonstop. Now I hope that fireworks get banned. I really do."

Resident Laraine Ito had been sensitive to the Asian cultural tradition of fireworks in Hawaii until Sunday’s night’s wildfire prompted her to call 911.

"Whoever was playing with those fireworks did it irresponsibly and without thinking," Ito said. "It really was scary. There were many, many homes involved. My personal feelings changed."

After Gov. Linda Lingle signed a bill allowing each county to enact stricter fireworks laws, the City Council scheduled a hearing for July 14 on the future of fireworks which is certain to draw arguments ranging from cultural practices to the effect on tourism to the health and safety of residents.

Fireworks likely were the cause of 10 post-Fourth of July fires yesterday on Oahu. In one, Waipahu revelers swept their fireworks trash into a container, which erupted in flames in their garage, causing $20,000 in damage, said fire Capt. Terry Seelig.

Firefighters also returned to Kalama Valley yesterday to extinguish hot spots along Kamehame Ridge, although residents were allowed to return to their homes.

The department normally responds to eight fire calls in a 24-hour period, but handled 51 between 12:01 a.m. Saturday and midnight Sunday — including a wildfire between Kalaeloa and Ko Olina — that taxed crews and equipment, Seelig said.

From the department’s perspective, the evening of July 4 had been shaping up quietly, with only the Ko Olina fire continuing to flare up.

But then residents along Kamehame Ridge reported that a huge percussive — and illegal — aerial firework landed in the brush along Kealahou Street at 9:30 p.m., half an hour past Oahu’s time limit to set off legal fireworks.

The fire quickly spread along the ridge and up the valley as "walls of flames 20 to 30 feet tall" came within 75 feet of homes with shake roofs, Seelig said. "Imagine looking out your back door and seeing the ridge on fire."

As the fire raced up the valley, at least 10 unrelated fire calls poured into HFD from 9:30 to 10 p.m., including two other brush fires and a report of a building fire in Waianae that turned out to be plumes of fireworks-related smoke, Seelig said.

With so much activity tying up 33 percent of the Fire Department’s companies, fire officials went to "Level 2 staffing," which meant prioritizing calls.

"We didn’t have the resources to send to them immediately, like we normally do," Seelig said.