The pilot of the helicopter which crashed in Vauxhall had requested to divert and land at Battersea due to bad weather, London Heliport said.
The helicopter crashed into a road in central London, hitting a crane on top of a central London tower block that was shrouded in fog early on Wednesday morning.
London Heliport in Battersea is less than two miles from Vauxhall.
Two people died in the crash, with emergency services naming the commercial pilot and someone on the ground as the fatalities.
It is believed the helicopter was not carrying passengers and it is not yet clear what the intended destination for the aircraft was.
Police said the helicopter was on a scheduled flight from Redhill, Surrey, to Elstree, Hertfordshire.
A spokesman for Elstree Studios posted on Facebook that they were not the intended destination, but added:. "Our thoughts are with everyone affected".
The helicopter exploded into flames, just streets away from the MI6 building and Vauxhall station and the site for the new US embassy.
Dense black smoke was billowing from the area, close to the river Thames after the helicopter spiralled to the ground in what eyewitnesses described as "a massive ball of flame".
One person has been critically injured while a number of others have less serious injuries.
A spokeswoman for London Ambulance Service said: "We have treated six patients, five for minor injuries and one patient for a broken leg. Four of the patients were taken to St Thomas' Hospital and two - a man and a woman - were taken to King's College Hospital.
Firefighters have now doused the blaze but earlier this morning flaming wreckage and aviation fuel covered the road as witnesses reported seeing cars on fire and hearing people screaming.
The crane at the St George's Wharf development is still "in a precarious position", London Fire Brigade said.
Investigations have begun as to why the Agusta 109 helicopter collided with the crane.
There are strict rules governing helicopter flights in the capital and the Air Accidents Investigation Branch (AAIB) team will want to know if proper procedures were followed.
Civil aviation expert Chris Yates, believes the weather on Wednesday morning could well have been a factor behind the incident.
He told the Huffington Post UK: "Fog is a particular issue. The question running round my mind at the moment is whether the fog appeared quite rapidly and caught the pilot unawares.
"It may well have disorientated the pilot and hence the reason why he apparently flew into this crane at the top of the building.
A spokesman for Berkeley Group, which owns St George, the development company for the building, said in a statement:
"We can confirm a helicopter collided with a crane at St George Wharf at 8am this morning. Our thoughts at this time are with the friends and families of those killed in this tragic incident.
"Emergency services are on the scene and authorities are investigating the circumstances. We are offering our full support and assistance to the emergency services."