West Ham say striker Michail Antonio is in a stable condition and "conscious and communicating" after a road traffic accident.
In a statement, West Ham said Antonio is "currently under close supervision at a central London hospital".
The Premier League club added: "At this difficult time, we kindly ask everyone to respect the privacy of Michail and his family.
"The club will make no further comment this evening, but will issue a further update in due course."
Essex County Fire and Rescue Service said it attended the scene of the accident on Saturday afternoon and released a man trapped in his car.