A massive explosion has sparked a huge fire and killed two people in an Indianapolis neighborhood where about three dozen homes were damaged or destroyed, US authorities say.
The powerful night time blast shattered windows, crumpled walls and could be felt at least five kilometres away.
Aerial photographs of the once-tidy neighborhood of one- and two-storey homes showed at least two had been reduced to blackened pits of debris.
Other homes had sections gutted by fire or holes in their roofs or exterior walls.
Siding dangled from the outside of other homes, and crumpled garage doors hung from houses nearby. Pieces of wood and other building materials littered the street and surrounding properties.
It wasn't clear what caused the blast about 11pm Saturday (5pm Sunday NZT). Firefighters responding to a call about a single house fire were surprised by a much bigger blaze.
The fire centred on four homes, two that were levelled and two others that only had the frames standing by the time the flames were extinguished, Deputy Chief Kenny Bacon said.
The damage extended two blocks in every direction, he said, and fire officials didn't initially realize the extent of it in the darkness.
City and fire officials said about two dozen homes were uninhabitable and would have to be torn down. Several more had severe damage but could be fixed.
Residents described a loud boom that shook their homes, blew out windows and collapsed ceilings. They rushed outside to find a chaotic scene with flames rising against the Indianapolis skyline to the north.
Bryan and Trina McClellan were at home with their 23-year-old son Eric when the shock wave from the blast a block away shook their home.
It knocked out the windows along one side of their house, and their first instinct was to check on their grandchildren, two toddlers who were in the basement. One held his ears and said, "Loud noise, loud noise."
Eric McClellan said he ran to the scene of the explosion and saw homes flat or nearly so.
"Somebody was trapped inside one of the houses, and the firefighters were trying to get to him. I don't know if he survived," he said, adding that firefighters ordered him to leave the area.
Once the flames were out, firefighters went through the rubble and damaged homes one at a time in case people had been left behind, Fire Lieutenant Bonnie Hensley said. They used search lights until dawn as they peered into the ruined buildings.
Along with the two people killed, seven people were taken to a hospital with injuries, Bacon said. Everyone else was accounted for, he said.
Four of the seven who were injured minor injuries, fire officials said. They did not provide details on the others or identify those killed.
An investigation was under way, said Bacon, who would not rule a gas leak in or out.
Dan Considine, a spokesman for Citizens Energy, said people usually smell gas when there is a leak, but the company had not received any calls from people smelling gas in that area.
Dan Able, a 58-year-old state employee who lives across the street from the two homes that exploded, said his first thought was that a plane had hit his house.
The blast was "a sound I've never heard before, it was so loud," he said. His windows blew out and a bedroom ceiling collapsed on his wife, Jan. He pulled her out, and they went outside.
"Both houses across the street were on fire, basically, just rubble on fire," he said.
The Ables and about 200 other people evacuated from the neighbourhood were taken to a nearby school. Some who had been sleeping arrived in their pajamas with pets they scooped up as they fled. Most eventually left to stay with relatives, friends or at hotels, but seven or eight remained through the night, sleeping on cots.
Some came back to pick up supplies from tables covered with baby food, wipes, blankets, and other essentials.