Two men aged 25 and 42 died in an accident involving a van early yesterday morning, with another 25-year-old man taken to hospital.
The Singapore Civil Defence Force (SCDF) was alerted to the accident at the junction of Bukit Timah Road and Mackenzie Road at about 3.10am, said a spokesman.
He added that the two men were pronounced dead at the scene by paramedics.
According to the police, the two who died were passengers while the injured man was the driver.
An eyewitness said the van had been speeding along Bukit Timah Road when it mounted a kerb on the left side of the road and crashed near KK Women's and Children's Hospital (KKH).
Associate engineer Anders Tan, 27, and his friend were in a car along the same road when the accident happened, and it was captured on the dashboard camera.
"My friend, who was driving the car, saw the van mount the kerb, producing sparks," said Mr Tan.
The injured driver was taken conscious to Tan Tock Seng Hospital, and The Sunday Times understands that he had open wounds on his left knee. He was later arrested for causing death by rash act, said a police spokesman.
The three men were friends who had just celebrated the driver's birthday, Shin Min Daily News reported yesterday.
The two passengers were private-hire car drivers and the older man was the godfather of the younger one, the report said.
It quoted the older man's sister as saying he had a son and was separated from his wife.
In video footage and pictures posted online and sent to citizen journalism website Stomp, the silver van is seen with its front severely damaged.
It is understood that it had slammed into a tree.
SCDF sent two fire engines, two fire bikes, three ambulances and two supporting vehicles to the scene.
Police investigations are ongoing.