**There has been a large explosion at a power plant in Connecticut, causing mass casualties, US media report.**Ambulances and fire engines have been called to the gas and oil-fired Kleen Energy plant in Middletown, south of the state capital, Hartford.
The Middletown Press newspaper said on its website that a gas pipeline had exploded, and that flames were shooting out of a pipeline at one point.
Witnesses said homes were shaken and black smoke could be seen for miles.