Two people were killed when their car plunged into a canal.
Witnesses described seeing dozens of emergency services vehicles race to the scene on the Feeder Canal near Bristol city centre after the car carrying two adults smashed through railings on Sunday evening before going "straight to the bottom".
Recording and rehearsal studio boss Steve Mallison, 44, was helping bands unload gear into the nearby RS Studios when the incident unfolded.
He said: "The car came down the road near Short Street and failed to stop when it got to the turning by Feeder Road.
"It went straight into the railings and literally went straight to the bottom.
"A middle aged couple in the street nearby were really traumatised by what they had seen.
"Loads of emergency services then raced down to the scene - I've never seen so many police cars and ambulances in quick succession.
"There's been a few cars which have gone in the river in the past 10 or 15 years we've been here, but none as bad as this.
"I knew straight away that it was very serious - especially after seeing 40 emergency vehicles and two river dive teams."
Avon and Somerset Constabulary said it was called to the incident at around 6pm.
A force spokesman said: "The bodies of two people have been located following the road traffic incident off Feeder Road.
"The incident took place when a car, driving from the direction of Short Street, failed to stop on Feeder Road and drove into the canal.
"At this time, the vehicle has yet to be recovered, but we do not believe anyone else was inside the car at the time of the incident."
Roads in the area remained closed for around five hours while emergency services teams worked to recover the vehicle and the two victims who police are yet to formally identify.
Anyone who may have witnessed the incident or seen the vehicle beforehand, is asked to contact 101 and quote log number 741.
A message on the force's Twitter page read: "Both bodies located at incident off Feeder Rd are adults. Please do not speculate online. Our thoughts are with both families."