Two people have died when a helicopter crashed into a crane in central London and cartwheeled to the ground.
The stricken aircraft exploded into flames after hitting the crane, on top of a tower block by the River Thames, before crashing into a street during rush hour.
Burning wreckage and aviation fuel covered the road as witnesses reported seeing cars on fire and hearing people screaming.
The Metropolitan Police said two people died at the scene and two had been taken to hospital. London Ambulance Service said two patients were taken to nearby St Thomas's Hospital with "minor injuries". King's College Hospital confirmed that a further two patients were being treated there for minor injuries.
Eight fire engines, four fire rescue units and around 60 firefighters plus officers attended the scene of the crash. London Fire Brigade said firefighters rescued a man from a burning car and brought a blaze caused by the crash under control. Four fire engines and two fire rescue units also attended reports of a crane in a precarious position. The brigade was called at 8am.
There were reports that the helicopter was flying across London from Gatwick to Elstree. It is believed that there were two people on board at the time. The aircraft is understood to be an AgustaWestland AW109, a lightweight, twin-engine helicopter with eight seats. Defence expert Paul Beaver said: "We have rules and there are procedures in place for helicopter flight. The River Thames is a safe place to fly through because aircraft can land in the water." He added: "It's much more challenging in reduced visibility. It's very much up to the pilot to fly the right route and do the right things."
Scotland Yard said: "Two people have been confirmed dead at the scene. We have no further details. Two have been taken to south London hospital. We await a condition update. We will confirm further details on the incident as soon as possible." Fire and rescue services were inundated with emergency calls as witnesses described the scene.
The aircraft appeared to have hit a crane on a newly built tower block on the south bank of the Thames. It crashed close to a railway line and a branch of Sainsbury's. London Fire Brigade confirmed that the crane at the St George Wharf development appeared to have been left "in a precarious position".
Video footage shot on a mobile phone showed an entire road blocked by burning wreckage and aviation fuel. The side of a building on one side of the street was also damaged by the flames. Passers-by stood watching as the wreckage burned. A motorcycle was also lying on its side in the road where it was abandoned.
The crane was on top of a building called The Tower, in the St George Wharf development, and is billed to be one of Europe's tallest residential towers. The building is only a few hundred metres from MI6 and is situated on a busy roundabout.