A British Airways (BA) engineer has died after two vehicles collided on the airfield at Heathrow Airport.
Two drivers were involved in the crash on the taxiway just after 06:00 GMT.
A man in his 40s suffered a cardiac arrest and died, despite attempts to save him at the airfield and on the way to hospital. Another man is in hospital with a suspected broken shoulder.
At least 20 BA flights were delayed by the incident, although the airfield remained open.
Passengers on one plane had to disembark after the crash, a Heathrow spokeswoman said.
She added: “Our deepest condolences go to the family and friends affected by this accident. We will be fully cooperating with the police in the investigation which will follow.”
A BA spokesman said: “We are deeply saddened by this tragic incident and are offering our full care and support to his family and colleagues.”
The Health and Safety Executive has been informed and there have been no arrests, the Met Police said.
It added that the deceased man has yet to be formally identified, but his next of kin had been informed.
Heathrow said the airfield remained open during the incident and it worked “to minimise disruption to passengers’ journeys”.
But a spokeswoman for BA said several of its flights from Terminal 5 were delayed by the crash.