The three people who were killed in a New Year's Eve crash between a car and a lorry near Heathrow airport were British Airways cabin crew, the airline has said.
A fourth person who was injured is also a BA employee. The four are believed to have been friends.
A BA spokesman said: "We're deeply saddened to learn of the death of our colleagues involved in a road traffic collision last night.
"Our thoughts are with their family and friends, who we are supporting at this distressing time."
The collision between a Mercedes HGV and a Toyota Yaris happened shortly before midnight on New Year's Eve.
Surrey Police said the lorry "ended up in Longford River" next to the road.
Two men aged 25 and 23, and a woman aged 20 - who were all in the Yaris, died at the scene.
A 25-year-old woman who had also been in the car was taken to hospital and is in a serious condition.
The lorry driver was also taken to hospital as a precaution.
British Airways pilot ambassador Jai Dillon tweeted: "Thoughts are with the friends and family of the 3 crew who were tragically taken from us last night whilst driving home from work to be with their loved ones for New Year."
Flying With Confidence, the airline's course for those with a fear of flying, tweeted: "Last night we tragically lost 3 members of our #BritishAirways family... our thoughts and prayers are with their friends and families during this very difficult time."
It is believed two of the four had finished work at about 6pm while the other two had been on a day off.
Pictures show the car on its roof as police investigated the scene, and the front of the lorry in the river.
Police said they were called to the crash in Stanwell - at the junction of Bedfont Road and Long Lane - at 11.39pm.
The road is near Heathrow's southern perimeter and was shut on New Year's Day, while work continued to recover the lorry.
No arrests have been made and next of kin have been informed.
The lorry was operated by air services provider dnata, which provides catering and cargo services to airlines.
A company spokesperson said: "We are fully assisting relevant authorities with their investigations. Our thoughts and condolences are with the families of those affected by this very sad incident."
One driver, who did not want to be named, told the Press Association that the road is "bad" and needs widening, adding: "You would be amazed how many accidents have happened down that road."
Sky reporter Laura Bundock spoke to residents in the area who said the junction "can be dangerous" and "there is a blind spot".
Sergeant Chris Schultze from the Surrey and Sussex Roads Policing Unit said: "Our thoughts are with the family and friends of those involved in this collision at what is an extremely difficult time.
"We are continuing to appeal for witnesses to what happened and would urge anyone who may have any video footage, CCTV or dashcam or any other kind, to get in touch with us.
"Please report any information via 101 and quote the reference number PR/P19303422."
In Manchester, a crash in the early hours of New Year's Day has left one man dead and five people with injuries - one of them is considered to be seriously hurt.
The 59-year-old driver of a Skoda died in hospital a short time after his vehicle collided with a Mercedes C43 AMG at 3.3am.
Police are asking witnesses to get in touch.