´óÏó´«Ã½

Some three million people have been left without power after violent storms hit the region around the US capital, Washington DC.

The storms swept from the Midwest states to the region around Washington, packing winds of up to 80mph (130 km/h).

The power outages left many sweltering without air conditioning amid a record-breaking heatwave.

At least 12 deaths have been linked to the storm, officials say.

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.

Washington's transit authority said most metro lines were back to normal service after the storm disrupted service on all lines during Friday night. But many Metrobus routes were subject to detours or delay due to downed trees and power lines.

Amtrak suspended services from Washington to Philadelphia.

The heatwave has seen all-time records smashed with temperatures of 104F (40C) in DC.

It was set to continue, said the National Weather Service - and it warned that another round of severe weather was possible.

The storms started in the Midwest and moved quickly eastward, hitting the mid-Atlantic states on Friday evening.

As well as gusty winds, users of the social network site Twitter reported spectacular, sustained displays of lightning. There were also reports of hail the size of a US quarter coin - just under an inch (2.4cm).

A state of emergency was declared in West Virginia where more than 500,000 were hit by power cuts.

Power companies said they were working hard to restore power to customers while some parts had water restrictions imposed after power cuts at two water filtration plants and other facilities.

The Associated Press news agency said the storms had been blamed for six deaths in Virginia, two in New Jersey, two in Maryland, one in Ohio and one in Washington DC.

In suburban Washington, residents were told to call non-emergency phone numbers or go to fire and police stations if they needed help because even 911 emergency call centres were without electricity.