Six police officers have had hospital treatment after diving into a river just after a car plunged into the water.
A woman inside the silver BMW died, and a man and a woman have been arrested on suspicion of causing death by dangerous driving after the incident in Bristol.
The victim was named locally as mother-of-one Namara Whisker, who is said to have given birth to a boy two months ago.
She is believed to have been at a nightclub in the city before getting into the car.
Friends have described the former business studies student, from the Easton area of the city, as "the kindest person you could ever meet".
The other four occupants of the car survived the incident in the River Avon. Two women are being interviewed as witnesses.
Floral bouquets now mark the scene of the crash in Passage Street, near Temple Meads train station, in the early hours of Saturday.
Ms Whisker was believed to be the front-seat passenger when the car, containing friends, left a bridge.
School friend Shawnika Sergeant, 22, said the pair had become close while studying at the then-Speedwell Technical College in Bristol.
Miss Sergeant said: "She was so pretty, bubbly and a special girl.
"I could not believe it when people started texting me this morning.
"I have known her for so long, it is hard to take."
Another woman, who arrived to pay tribute at a makeshift shrine next to the river, said she was with Ms Whisker in a Bristol nightclub until minutes before the crash happened.
The woman, who asked not to be named but said she was a distant relative, said: "We saw each other in the club, we gave each other a hug.
"I am so glad I had the chance to do that now, because I realise it was goodbye."
Another friend said Ms Whisker was a guest at her five-year-old son's Christening.
She added: "Namara has a two-month-old son, I can't believe he is going to grow up without his mummy."
Shattered glass marked the scene after the crash, with a temporary barrier in place to cover the missing section of iron railing.
Police officers said the six police were taken to hospital as a precaution. Officers are not looking for anyone else in connection with the crash.