Two people died when a helicopter clipped a crane at the top of a building in central London Wednesday, scattering debris to the ground as it burst into fire.
The BBC, quoting police, said one of the victims died in the helicopter, without giving further details. Reports said earlier there was only one person on board the AugustaWestland AW 109.
"There was a massive explosion. People were shouting and screaming," an eyewitness told the BBC. One person was rescued from a burning car, witnesses said.
People who were on their way to work during the morning rush hour reported parts of an aircraft falling out of the sky before the helicopter "plummeting down."
Police said two people died in the accident, in Wandsworth in south-east London. The helicopter reportedly came down in misty weather conditions near the Battersea heliport, used chiefly by private plane owners.
Ambulances and more than 60 fire brigades rushed to the scene, as people were being evacuated from homes and offices. The fires were extinguished around two hours after the crash at 0800 GMT.
"I could see the top of the crane was shaking on the top of the building. It was very foggy so the helicopter probably couldn't see it," said one witness.
The accident, not far from Waterloo train station and a major bus depot, caused long traffic delays on the roads and on the public transport network.