The crash happened on the A40 in west London when a car reportedly involved in a burglary earlier in the night was chased by police.
Metropolitan Police said its officers responded to reports of an aggravated burglary in Harrow, northwest London, at around 8.40pm on Sunday.
In response, they pursued the car, which drove onto the wrong side of the carriageway.
It then collided with a coach near the junction of Kingsdown Avenue, Acton at around 9pm.
A man and a woman were pronounced dead at the scene and a second man is in hospital for treatment.
“Looks like a car crashed head-on against a coach”
All three were in the car being pursued when it crashed.
There were no reports of other serious injuries, and details of the number of people on the coach haven’t yet been released.
The Met said police cars didn’t follow the vehicle when it drove on the wrong side of the road.
Road closures remain in place while London Ambulance Service and London Fire Brigade are at the scene.
Scotland Yard said the Directorate of Professional Standards and the Independent Office for Police Conduct (IOPC) had been informed of the incident.
In a tweet, Ealing MPS said there had been an accident on the A40 and warned drivers to expect delays.
One nearby resident Lauren claimed on Twitter she had “seen and heard at least seven police cars, a helicopter that’s been circling and now an ambulance hearing from west London on the A40 road into central London”.
Another resident shared a picture from the scene of the crash in response, tweeting: “Just walked up there, looks like a car crashed head-on against a coach.”
This is a breaking news story and is constantly being updated.
Please refresh the page regularly to get the latest updates.
Reporters working on dailystar.co.uk will be working to source the latest information, reaction, pictures and video related to this story.
You can also follow us on Twitter @Daily_Star to get the latest news updates 24 hours a day.
Or download the Daily Star app for flash alerts on the biggest stories of the day.