Two subway trains have collided in Washington, killing nine people and injuring more than 70.

One train rammed into the back of the other, crushing the rear carriage and trapping many of the passengers inside.

The accident, which happened during the evening rush hour, is the worst since the subway system opened more than 30 years ago.

A female driver of one of the trains was among the dead.

Dozens of people were taken to hospital after the crash between the Fort Totten and Takoma Park stations on the Metro system’s red line, near the Washington-Maryland border.

Washington fire spokesman Alan Etter said crews had to cut some people out of what he described as a "mass casualty event".

More than 200 firefighters were called to the scene and Washington DC mayor Adrian Fenty said they were looking through the carriages for survivors.

He said: "It is my present understanding that this would then be the deadliest accident in the history of our Metro train transit system."

Passenger Jodie Wickett, a nurse, said she was seated on one train, sending text messages on her phone, when she felt the impact.

She said she stayed at the scene and tried to help other passengers.

"The people that were hurt, the ones that could speak, were calling back as we called out to them," she said.

"Lots of people were upset and crying, but there were no screams."

Officials said it was too early to know what caused the accident on the heavily-used underground system.

The collision comes more than two years after a subway train derailed near downtown Washington, injuring 20 people.

Via news.sky.com