Motorists are warned that Kew Bridge Road has been closed in both directions at the Green Dragon Lane junction, following reports of a collision at around 1.15pm.
Emergency services including police, ambulance and air ambulance are at the scene of the accident.
There are unconfirmed reports that a police chase starting in Hounslow before the crash in Brentford, which also left a lamp post damaged.
Hounslow MPS has urged people to avoid the area on social media site Twitter.
A number of bus routes have been placed on diversion including 65, 237 and 267.
We have contacted the London Ambulance Service and Metropolitan Police for further information.
Three people were later rushed to hospital with injuries as police confirmed a car chase led to the crash and arrests had been made.