Commissioner of Police Joe Chow Yat-ming said that the constable, 31, had regained consciousness but remained in the intensive care ward of Tuen Mun Hospital and was still in a critical condition.

Chow declined to further discuss the progress or the direction of the investigation.

The accident took place on Kong Sham Western Highway shortly before 5.30pm on Friday when a Citybus driver lost control of his northbound bus. The route B3X double-decker bus, travelling from Tuen Mun town centre to Shenzhen Bay port, hit the back of a police vehicle that had stopped on the road to handle a traffic incident.

The constable had already left his vehicle to inspect another bus that had broken down when the collision pushed the police van into the fast lane, causing it to hit a taxi.

After the crash, the double-decker bus continued to slide forward to the left, with the officer falling off the bridge when he tried to avoid the vehicle.