The Honolulu Fire Department has determined a child playing with a lighter caused a fire and explosion at Palolo Homes.

The fire and blast occurred at about 12:30 p.m. Tuesday in the second- story bedroom of Unit C in Building 27 at 2187 Ahe St. Honolulu Fire Department spokesman Capt. Scot Seguirant has said four occupants — two adults and two children — were alerted to the fire when they smelled smoke, and quickly escaped.

A medical oxygen tank inside the unit then exploded, causing injuries to the property manager, 61, and resident services manager, 58. Both were standing at the threshold of the unit to investigate a report of a fire when the explosion occurred.

Firefighters responded and extinguished the fire.

Damage to units B,C and D in Building 27 was estimated at just over $1 million to the structure and $50,000 to its contents. Damage to units B,C and D in Building 25, on the makai side of Building 27, was estimated at $15,000 to the structure.

According to Dave Naka­mura, executive director of the Mutual Housing Association of Hawaii, which owns the 302-unit public housing unit, the children’s grandparents were inside the unit at the time the fire broke out.

Seguirant said, “When children are not supervised as well as have ready access to matches or lighters, their likelihood of playing with fire increases. Securing matches and lighters away from children and being within view of the child greatly reduces opportunities of unwanted fire.”

Sixty-year-old Palolo Homes resident Felicia Kobeney said she was still shaken a day after the blast.

“I was so shocked,” she said as she recalled hearing a “big boom” Tuesday while she was reading her Bible in the living room of her apartment. She and her husband, who reside in Unit E of Building 27, two doors away from Unit C where the blast occurred, safely escaped their apartment.

Emergency Medical Serv­ice has said the property manager sustained first- and-second-degree burns to about 30 percent of his upper body, and the resident services manager sustained second-degree burns to about 25 percent of her upper body. Paramedics treated and transported them to a hospital in critical condition and serious condition, respectively.

The housing association’s website identifies the property manager as Gregory Skaltsas and the resident services manager as Dahlia Asuega.

EMS also treated and transported a 70-year-old resident to the hospital for smoke inhalation. He was listed in stable condition.

Kobeney recalled one of her window screens blew off at the time of the blast. She helped her husband, 61, who has difficulty walking after he suffered a stroke in 2001, into a wheelchair before they escaped their apartment. The couple and their 16-year-old grandson are now staying with family members.

Nakamura said, “It’s not safe for the residents to go into building.” Structural engineers were to inspect damaged buildings Wednesday or today.

Meanwhile, the housing association is working to relocate six displaced families into vacant units on the property. “The damage to several apartments (is) extreme. They won’t be moving back anytime soon,” Nakamura said.

A crew from contractor MD Restoration arrived Wednesday morning to clear debris from the grounds around Building 27, where broken window glass was strewn on the sidewalks and grass.

Wood covered about eight windows that were blown out by the explosion at Building 25.