Massive blast from unknown cause kills at least two people and flattens homes in largest city of US state of Indiana.

An explosion has levelled two Indianapolis homes, killing at least two people and forcing about 200 people from their neighbourhood, authorities said.

“This looks like a war zone; it really does … Police officers and fire department officials remain at the scene searching for other possible victims“ – Lt Bonnie Hensley,

Indianapolis Fire Department

The powerful nighttime blast on Sunday shattered windows, crumpled walls and inflicted other damage on at least 14 other homes.

Four people were taken to hospital with minor injuries after the explosion and fire, the Indianapolis Fire Department said in a statement.

Fire Lt Bonnie Hensley said firefighters put out the flames and then went through the rubble and damaged homes one at a time in case people had been left behind. Two bodies have been recovered.

Some witnesses said in televised reports that they heard people screaming “Help me! Help me!” after the explosion and fire, and that two parents and two children were safely pulled from one house that caught fire.

“This looks like a war zone; it really does,” Hensley told the AP news agency. “Police officers and fire department officials remain at the scene searching for other possible victims.”

She said they used search lights until dawn as they peered into the damaged and ruined homes.

The fire department has not released the names of those killed.

Hensley said one body was found in one of the levelled homes after the fire was put out, and that at least 14 other homes were damaged in the area by the Saturday night blast’s shock wave or flying debris.

‘Nothing left’

The explosion was heard for miles around, but authorities said they had no immediate information on the cause. The fire department and other agencies were investigating.

People who were asleep when the blast happened were evacuated in their pajamas, scooping up their pets as they left. They left what some described as a chaotic scene of tall flames rising on the Indianapolis skyline.

Survivors reported shattered windows, caved-in walls and garage doors knocked off their hinges. Of the two homes that were levelled by the blast, Hensley said: “There’s nothing left”.

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.

All power, gas and other utilities in the area were

shut off as a precautionary measure [EPA]

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 was holding his ears and saying “Loud noise, loud noise”.

Eric McClellan said he ran afterward 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.

All power, gas and other utilities in the area were shut off as a precaution as emergency officials swarmed the site.

About 200 people were taken to an elementary school, where some milled about in pajamas and coats they had grabbed as they fled. Some had their dogs on leashes, and one woman had evacuated her home with a cat.

Most eventually left to stay with relatives, friends or at hotels, but 15 to 25 remained through the night, sleeping on cots.

Pam Brainerd, a 59-year-old hospice nurse, said she was asleep when the explosion blew out the upstairs windows in her house.

“I was sleeping on the sofa and all of a sudden, my upstairs windows were blowing out and my front door was falling in,” Brainerd said. “My front door came off the frame. It was the largest bang I’ve ever heard.”