A pregnant woman and her unborn child have died after the car they were travelling in was hit by an unmarked police car.
The Metropolitan Police said the unmarked police vehicle was in collision with a member of the public’s car on the A20, near the junction with Kidbrooke Park Road, in Eltham, south-east London.
The 38-year-old heavily pregnant woman and her unborn baby died as a result of their injuries.
London Ambulance Service, London Fire Brigade and London's Air Ambulance all attended the scene at 18:15 BST on Thursday.
The woman's next of kin have been informed, the Met said.
Det Ch Supt Trevor Lawry said: "My heart goes out to the woman's family and friends who have lost their loved ones in these tragic circumstances."
Two officers who were in the unmarked car were also taken to hospital following the collision, and have since been discharged.
Det Ch Supt Lawry said an investigation was under way and the incident had been referred to the police watchdog, the Independent Office of Police Conduct (IOPC).
The IOPC confirmed it was investigating the incident and appealed for witnesses.
IOPC regional director Mel Palmer said: “It is important we establish all of the circumstances surrounding this incident and our investigation is in its very early stages.
"This is a busy road, and the collision happened in the early evening when people are likely to have been travelling."
She extended her sympathies to the family and friends of the woman.
The Met confirmed it was one of their own vehicles and not from a neighbouring force.
It is unclear whether the police car was responding to an emergency at the time, and the Met said this question would form part of its inquiries.
IOPC figures for 2023/24 show that six people died in traffic-related interactions with Metropolitan Police officers - the figure is 32 for all police forces in England and Wales.
Flowers have been left at the scene of the crash.
One of the tributes laid on the road said: "My deepest thoughts are with you, your baby and your family and friends.
"The most awful tragedy that should never have happened and hope your family get some justice. RIP beautiful lady and your baby."
'Terrible tragedy'
Some residents in Eltham said the junction where the crash happened was "one of the most dangerous" in south-east London.
"This is a very dangerous road. I didn't hear anything but when I looked out of the window I saw loads of police cars and emergency service vehicles," one resident said.
"The police were here for ages and the road didn't start to open properly until Friday morning."
Neighbours have suggested the incident was almost "unsurprising" given the speed at which drivers travel on the route.
One said: "They drive really recklessly and it's a very busy road, so I see how it could happen."
Another resident said they had been "brought to tears" by news of the incident and recalled seeing "loads of emergency vehicles" throughout the night.
Clive Efford, the Labour MP for Eltham and Chislehurst, said: "This is a terrible tragedy, and my heart goes out to the family of the victims.
"The incident is now under investigation by the Independent Office for Police Conduct and there are many questions that I will be putting to them which I hope they will be able to answer in their final report."