A British Airways engineer has died after two airport vehicles crashed at Heathrow.
A yellow airside operations pick-up truck was one of the vehicles involved.
They are often driven around the airfield at high speed by Heathrow staff carrying out tasks such as directing aircraft and inspecting the runways.
A BA spokeswoman said: "We are deeply saddened by this tragic incident and are offering our full care and support to his family and colleagues.
A Heathrow spokeswoman said: "We can confirm that following a serious accident involving two vehicles on our airfield, an airport colleague has passed away.
"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 man, aged in his 40s, has died after two airport vehicles crashed on the airfield at Heathrow, Scotland Yard said.
In a statement, Scotland Yard said: "Police were called at 6.06am on Wednesday, February 14, following a collision between two airport vehicles on the taxiway at Heathrow Airport.
"Officers attended with London Ambulance Service colleagues.
"One male is believed to have sustained a broken shoulder; his injuries are not life-threatening or life-changing.
"Another male, aged in his 40s, was taken to a west London hospital with serious injuries. He has since died.
"Officers have informed next of kin. We await formal identification.
"A post-mortem will be scheduled in due course.
"There have been no arrests.
"The Health and Safety Executive has been informed.
"Officers from the Met's Serious Collision Investigation Unit are investigating."
There has been a "serious accident" on an airfield at Heathrow Airport.
Airport officials say it involved two vehicles on the airfield at Terminal 5, and hundreds of passengers have reportedly been evacuated from planes.
In a statement, the airport said it was "We are working closely with the emergency services and updates will follow".
Hi, we are dealing with a serious accident involving two vehicles on the airfield. The airfield remains open and we will work to minimise disruption to our passengers’ journeys. Thank you.
— Heathrow Airport (@HeathrowAirport) February 14, 2018
The airport said the incident involved "two members of staff", adding: "An investigation is underway and we are working with the police. This incident didn't involve any passengers and is not expected to cause any impact on journeys today."
Despite the airport insisting the incident would not impact journeys, a number of passengers posted to Twitter that they had suffered problems.
Alastair MacLeod tweeted: "Apparently there has been an accident on one of the runways at @HeathrowAirport and many planes (including this one) are parked on the apron with unspecified delays of 'hours'. No public news of this and no useful updates from @British_Airways - anyone out there know any more?"
Apparently there has been an accident on one of the runways at @HeathrowAirport and many planes (including this one) are parked on the apron with unspecified delays of “hours”. No public news of this and no useful updates from @British_Airways — anyone out there know any more?
— MacLeod of MacLeod (@macleodadg) February 14, 2018
After Heathrow responded to say the accident was not expected to impact journeys, Steven Ross replied: "With respect, it is impacting journeys departing B gates - BA710 to Zurich delayed by +2 hrs and aircraft change required. Sending good wishes to injured staff."