Up to two million people are without power after violent storms hit the region around the US capital, Washington DC.

The storms swept across West Virginia, Virginia, Washington and Maryland, with wind speeds of up to 75mph (120 kph). The power outages left many without air conditioning after a day of record-breaking 104F (40C) heat.

The storm is locally referred to as a “derecho” – a violent, straight-lined windstorm associated with a fast-moving band of severe thunderstorms.

It left behind felled trees; streets littered with fallen branches and downed power lines.

The storms capped a day of sweltering temperatures. Services on all Washington metro lines was affected, with trains sent to their end points after trees fell across the tracks and power was lost.

Nearly two million people were left without power, reported Associated Press, which said that a state of emergency had been declared in West Virginia where more than 500,000 were hit by power cuts.

Associated Press quoted police in Springfield, Virginia as saying a woman had died when a tree fell on her home at the height of the storm. The Washington Post said another death in the same Fairfax County had also been attributed to the storm.

“High temperatures reached record levels in the mid-Atlantic states today [Friday],” said the National Weather Service.

“In fact… new all-time highs for June… and even all-time highs for any year… were established,”.

It said the heat should become less intense over coming days, but warned that thunderstorms and potentially severe weather remained a threat.