Three teenagers and a man died, and two teenage girls were taken to hospital with serious injuries, following the two-car collision in Horsforth.
Police said a grey Seat Leon was involved in a collision with a grey Seat Alhambra taxi people carrier, at about 2.40am on Saturday on Broadway, near Bank Gardens.
Four men, aged 18, 19, 19 and 21, who were travelling in the Leon, were killed in the crash.
Three of the four young men who died have now been named in local reports as Declan Grove, Matthew Walshaw and Brandon Frew.
Chara Andrews, 19, said he had grown up with the young men and felt "absolutely empty" following the tragic news.
He said: "When I found out this morning I didn't want to believe it.
"They were the best set of lads you could ever meet.
"We've had some of the best times and I feel happy now remembering it.
"I know they're all together and looking down on us at the moment.
"Everybody loved them all and we're all meeting up tonight to toast them - we are all pulling together and remembering the good times."
The male driver of the Seat Alhambra, a 42-year-old taxi driver from Bradford, was today in hospital with injuries described as "serious but not life-threatening".
Adam Omar, 34, who was asleep with his partner at when the crash happened, told how he heard a "skid" and then a bang which was like an "explosion".
He went outside and saw "half a car" in the middle of the road and a taxi also stationary in the road.
Another neighbour, who did not want to be named, said her son had been awoken by the sound of the crash.
She said: "He looked out of his window and saw plumes of smoke and debris.
"A taxi was facing out of the junction and the car was facing into it.
"Another passing taxi driver stopped and got out of his car and went over to the silver car.
"He saw him someone out of the of the back of the car on the driver's side then he went to get the taxi driver out.
"The taxi driver was walking wounded but seemed OK."
As police removed cordons and re-opened the road to traffic today, groups of mourners arrive at the scene to lay flowers and comfort each other.
A group of more than 20 people hugged each other and cried as two women taped flowers to a lamppost next to the crash scene.
One read: "To my beautiful son. You were so loved and adored. Rest in peace. Always in my heart and mind forever I love you so much. Mum."
Another read: "To Matty your always in our hearts forever, words cannot describe the love I have for you little bro, keep smiling up there kid.
"R.I.P Love you always"