Police confirmed a man died in an incident this morning which forced around 20 flights to be delayed and a departing plane to be evacuated.
The incident took place at 6am near Terminal 5, when a “serious accident involving two vehicles” took place on the airfield.
Paramedics were scrambled to the scene as a plane was left stranded on the runway unable to take off.
A man then suffered a cardiac arrest and “extensive efforts were made to resuscitate him” as he was rushed to hospital fighting for life.
But Scotland Yard have confirmed the man, in his 40s, later died.
The second man involved in the crash has suffered a broken shoulder, and was also taken to hospital.
A Metropolitan Police spokesman said: “Police were called at 06:06hrs on Wednesday, 14 February following a collision between two airport vehicles on the taxiway at Heathrow Airport.
“Officers attended with London Ambulance Service colleagues.
“One male [no further information], 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.
A London Ambulance Service spokesman said earlier: “We were called at 6.03am today to Heathrow Airport, to reports of a road traffic collision. We sent an incident response officer, an advanced paramedic, a cycle responder and three ambulance crews.
“We treated two patients – both men. One was treated for a shoulder injury and taken to hospital.
“The second later went into cardiac arrest and extensive efforts were made to resuscitate him both at the scene and on the way to hospital.”
It is reported an area around a number of gates were closed off to stop planes from departing following the incident.
It is also said some passengers who had boarded planes when the incident took place have since returned to the terminal building.
The majority of the flights delayed this morning were from Terminal 5.
A Heathrow spokesman said earlier: “We are dealing with a serious accident involving two vehicles on the airfield.
“We are working closely with the emergency services and updates will follow.
“The airfield remains open and we will work to minimise disruption to our passengers’ journeys. We apologise for any inconvenience caused.”