One person was critically injured when a self-driving shuttle bus crashed into a tree in Whitby Thursday afternoon.

Durham police said the collision happened in the area of Watson Street West and Victoria Street around 4 p.m and involved a Whitby Autonomous Vehicle Electric (WAVE) shuttle.

"There was one operator on board," Acting Sgt. George Tudos said. "No pedestrians or any passengers so that one person did suffer critical injuries."

The person was taken to a trauma centre, where he remains in life-threatening condition.

The cause of the crash is unknown.

"We are doing a parallel investigation with the Ministry of Labour to try to determine exactly what happened," Tudos said.

The WAVE bus hit the streets of Whitby last month as part of a pilot project “to learn about how autonomous technologies can contribute to safer, more sustainable and connected transit and traffic operations.”

The self-driving bus travels a six-kilometre route that begins and ends at Whitby GO Station, operating at a speed of no more than 20 kilometres per hour. It is equipped with radar and a 360-degree camera to scan for obstacles, allowing it to adjust and navigate around them.

According to Durham Region Transit, a trained safety attendant is on board all the time and can manually take control of the vehicle at any time if required.

- with files from CTV Toronto's Carol Charles