The tragedy occurred after helicopter crashed into a construction crane on top of a residential block in central London.
"Two people have been confirmed dead at the scene. We have no further details," police said in a statement. Two others had been taken to hospital it added.
Helicopter crashes in London, no casualties reported:
A helicopter crashed near the Vauxhall railway station in central London near the Thames River during the rush hour on Wednesday. Fire services were pressed into action after a wreckage was seen burning in the street. Black smoke was seen engulfing the sky over the river.
City police said it was too early to say if there was any death in the crash. They said the helicopter might have collided with a crane on top of a building under construction. Some witnesses later also said that collision with a crane atop a building led to the accident.
Sources said the Augusta 109 civilian helicopter, which was just carrying one person, its pilot, was flying low in the crowded part of the capital and might have crashed into the crane due to poor visibility caused by fog.
The helicopter hit two cars after the clash, leaving both charred.