The Hammers have delivered an update on Antonio after he was taken to hospital on Saturday afternoon.
The club said: "West Ham United can confirm that Michail Antonio is in a stable condition following a road traffic accident this afternoon in the Essex area.
"Michail is conscious and communicating and is currently under close supervision at a central London hospital.
"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 have also stated: "Crews were called at 1.02pm this afternoon after reports of a road traffic collision involving one car.
"Firefighters reported that a man was trapped in his car and worked to release him by 1.45pm. The casualty was left in the care of the Ambulance Service."
Essex Police said officers were investigating a serious crash involving a Ferrari.