At least two fatalities are reported from an explosion at a power plant under construction site in Middletown, Connecticut.

The explosion happened at the Kleen Energy natural gas and oil plant under construction on River Road around 11:30 a.m. Here are the details News Channel 8 has learned from authorities at the command post:

• There are two fatalities.
• This was a working construction site
• Workers were doing a ‘blow down’ to clear gas from the lines when the explosion occurred
• No word on where the workers are from
• Fire is completely out
• Local residents told to stay away
• Windows at Conn Valley Hospital in Middletown broken out by the explosion

Two LifeStar helicopters were called to the scene. One has taken off carrying one patient. We do not know any details about the person’s injuries.

State police have deployed detectives and cadaver dogs to the scene to help Middletown authorities, state police spokesman Lt. J. Paul Vance said.

There are reports there may have been 300 people in the building at the time of the explosion.

Bernadette Nyland was outside in her yard with her dogs when she heard the blast. “They were doing the firing of the engines this morning and so something went wrong and it blew up and flames came shooting up almost as tall as that stack,” she said.

There are reports that homes near plant have been damaged by the explosion. It was felt as far away as Wallingford, North Haven, North Branford and Cheshire.

News Channel 8’s Darren Kramer said on Twitter was outside in North Guilford when he heard the explosion. “Sound was huge and low. Lasted several seconds. Assumed sonic boom.”

Another Twitter follower named Jennifer said via Twitter, “First thought was earthquake or huge gust of wind–whole house shook, very brief but powerful.”

Shelby wrote on Twitter “my whole town was writting on facebook asking if it was a easrthquake, Northford”

Others heard or felt the explosion in Oxford and as far away as Mystic.

Dozens of emergency personnel from multiple towns and agencies are on the scene. In the rush to offer assistance however it may be needed, Danbury Mayor Mark Boughton said via Twitter “Our HazMat and Decon trailer are on standby for Middletown.”

Hospitals in Middletown and Portland have gone into a disaster mode. Bridgeport Hospital, which has a burn center, is on standby, but a spokesman says they have not yet been alerted that any patient is heading their way.

Governor Jodi Rell was on her way to the scene.