Beatrice Johnston recalled the three young siblings who lived nearby as the sort who gleefully ran around the neighborhood and splashed about in a small pool on the sidewalk in front of their home.

On Sunday, she watched in horror as their house became engulfed in black smoke from a fire that would kill the three children and two young cousins. Two adults escaped — one who jumped in the wading pool on the sidewalk.

"You can't explain tragedy," Johnston said.

The one-alarm fire started around 8 a.m. Sunday in a two-story stucco rowhouse in the city's Kensington neighborhood (search) and took just nine minutes to extinguish, Fire Commissioner Lloyd Ayers said.

But the attempted rescue of the children was hampered by the security bars on some of the home's windows, he said.

"The bars usually keep us from getting in and keep residents from getting out," Ayers said. "There were so many things that came together to spell disaster."

It was not known whether the home had smoke detectors.

Officials would not release the names or ages of the victims, but neighbors said the boy and four girls ranged in age from 6 months to 6 years old. Three were siblings and the other two were their cousins, neighbors said.

Firefighters combed through the house Sunday, carting out debris as investigators tried to determine what sparked the fire. Authorities declined to say if there were signs of foul play, but said they would be looking for possible code violations.

Two adults — who were believed to be the parents of the three siblings — managed to escape by jumping from a second-floor window. They were both seriously injured.

Irene Weal, who lives across the street, said the family lived in the home on the block of well-tended brick and stucco houses for a year or two. She called 911 when she saw the smoke and flames pouring out of the home.

"It could have happened to my kids," she said.

Investigators said they believe the fire started on the first floor. Four of the children were found on the second floor and the fifth was on the first floor.