A man and woman in their 70s have died after the car they were in was hit by a van which was being pursued by police.
Scotland Yard said police officers spotted the van being “driven erratically at speed” which failed to stop.
The vehicle collided with a Citroen C3 on Footscray Road, Eltham, at just after midnight on Saturday.
Paramedics were called, but both the male and female in the car were pronounced dead at the scene.
Police later confirmed the van was a rental vehicle.
Neighbours said the vehicle, which had severe damage to its front, was removed several hours later.
The driver of the van was arrested on suspicion of driving whilst over the alcohol limit, driving while unfit through drugs and death by dangerous driving, the Metropolitan Police said.
Deputy Commissioner Steve House added: "Whilst this collision and the circumstances surrounding it will be investigated, I, on behalf of the Metropolitan Police Service, extend sincere condolences to the family and friends of the two people who died as a result of this incident. Our thoughts are with them at this time."
Neighbour Mahmut Hasan, 57, said he was asleep at the time of crash but was awoken after the Citroen came to a stop in the back of his Honda Jazz.
“I came down and saw them (emergency services) trying to resuscitate the older couple for a long time.
“I saw the passenger side had a walking stick next to it. Their whole car was a mess. Very badly damaged. The front was gone.
“(My car) is a write-off. The whole of the side is damaged.
“I’ve had the car about six years and I’ve only done 3,000 miles in it.
“But at the end of the day it doesn’t matter because it’s just metal and rubber, and two people have sadly lost their lives.”
Council staff were busy on Saturday morning putting down sand on the road, which has 30mph speed limits.
Tyre marks could be seen across the carriageway and on a grass bank, with damage to a wooden post.
Mr Hasan said: “The road can be quite dangerous though. Cars can go very quickly along here.
“I’ve lived here for 26 years and some cars really speed along.”
Neighbour Hussein Dervish, 65, said: “I was in the back of my house when I heard just a loud bang. Even with the double glazing and all that, I still heard it.
“I went outside and saw the car and the van. I said to the police officer: ‘I hope they (the elderly couple) are okay?’ But the policeman said they weren’t.
“I don’t know what happened here. But there was another smash a few weeks ago just down the road.
“Sometimes they come along here at 70mph or 80mph, with their modified engines.”
The Independent Office for Police Conduct is investigating the incident.
A spokesperson said: “Our investigators have attended the scene and post incident procedures to gather the initial evidence. Our investigation will focus on the police’s actions prior to the crash.
“Our thoughts are with the family and friends of the deceased and all those affected by this incident. We will make contact with the family at the appropriate point to explain our role.”