A wild sambar deer has died after it wandered onto the Bukit Timah Expressway (BKE) near Mandai Road and caused a three-vehicle accident early yesterday.

Wildlife Reserves Singapore said in a statement that the animal was euthanised on welfare grounds at 8am, after its injuries were found to be too severe.

The police said they were alerted to an accident involving a taxi, a car and a motorcycle on the BKE, towards the Pan-Island Expressway, after the Mandai Road exit at 4.40am.

A 46-year-old taxi driver suffered cuts on his head. He was conscious when taken to Ng Teng Fong General Hospital.

The Straits Times understands that the accident occurred as the motorcyclist was trying to avoid the deer, which prompted the car and taxi drivers to apply their emergency brakes. Police investigations are ongoing.

Dashboard camera footage shared on social media showed the rare animal struggling to get to its feet in the middle of the expressway, as vehicles inched past it on both sides.

A wildlife rescue team from the Animal Concerns Research and Education Society (Acres) headed to the location after receiving a call at about 5am, said its deputy chief executive Kalai Vanan.

"The deer was immobile, suggesting severe injuries," he added.

A wildlife rescue team from WRS, comprising five zookeepers and a veterinarian, was alerted by Acres at about 6.45am. WRS said there were multiple abrasions and wounds on the deer's body, and fractures on its hind legs.

The 120kg adult male sambar deer was sedated and taken to the animal hospital in WRS for emergency medical attention. It was determined that the deer's injuries were too severe and it was euthanised, WRS said.

Motor vehicle incidents are among the top threats to local wildlife, added WRS, as it urged motorists to slow down on roads along forested areas and heed wildlife crossing signs.

Sambar deer are usually deep forest dwellers, although they may venture to the forest fringes due to disturbances or to forage for food.