Five young people have been killed in a road accident, with police saying they had "involvement with the vehicle immediately prior to the crash".
Diana and Chris Farrell said they could not sleep after the accident
The accident happened in St Leonards, East Sussex, in the early hours.
A Sussex Ambulance spokeswoman said all five occupants of a blue Metro car died at the scene.
The Independent Police Complaints Commission (IPCC) said officers in a marked vehicle saw the car after receiving a report about it.
It crashed two minutes later on Battle Road, at 0142 BST.
Diana and Chris Farrell said they were woken by a thud and looked out of their window to see the Metro on its side on their driveway.
"It was behind my car which was parked in the driveway," said Mrs Farrell.
"I couldn't believe how much damage there was with so little noise.
"There was a lot of smell of petrol fumes and there was a police car in the road."
Mr Farrell said: "They removed three bodies during the early hours and then two this morning.
"I just couldn't believe that five kids had died."
The couple said they heard no police siren or screeching of tyres.
An IPCC spokeswoman said a senior investigating officer had been sent to the scene.
The spokeswoman added: "Issues such as whether or not a police car was following the car, how close it was and whether or not its blue lights were on, for instance, will all be subjects of the inquiry.
"At this stage it is far too early to say what the exact involvement of the police and the vehicle was.
"We will be managing the inquiry, but the police will be running it. We have no further details at this stage."
IPCC duty commissioner Mike Franklin said: "My condolences go to the families and friends of all those involved in and affected by this tragedy.
"This is a terribly distressing incident and I will ensure the investigation finds out what happened and why.
"We still have next of kin to be contacted and it's important that any judgments are reserved until those things have taken place."
Sussex Police said they were "investigating the circumstances of the tragedy".
The road was closed for several hours for investigations.