A British Airways engineer has died after two airport vehicles crashed at Heathrow.
Another male sustained a suspected broken shoulder in the crash near Terminal 5 shortly after 6am on Wednesday.
The deceased, aged in his 40s, was taken to a west London hospital but could not be saved, the Metropolitan Police said.
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."
The Health and Safety Executive was informed and officers from the Metropolitan Police's serious collision investigation unit went to the scene.
No arrests were made.
At least 20 BA flights from Terminal 5 were delayed and passengers were ordered to leave an aircraft which was unable to take off because of the crash.
The airline apologised to passengers and said it was doing "all we can" to ensure delayed flights depart as soon as possible.