Police have closed part of Kensington Road in Northolt following a serious collision near Smiths Farm.
Emergency services were called to the area after reports of a crash involving a car and electric bikes.
Local residents reported seeing a police cordon in place and said an air ambulance had also attended the scene.
Road taped off by police
Witnesses said Kensington Road near Smiths Farm was blocked by officers while emergency services dealt with the incident.
Unconfirmed reports from people in the area suggest two rented electric bikes and a car may have been involved.
The condition of those involved has not yet been officially confirmed.
Police have taped off part of the road while enquiries continue.
Motorists are being advised to avoid the area where possible.
Further information will be published once confirmed by emergency services.
