Why did car suddenly cut across lanes and brake -- causing accident?

A car was caught on camera cutting across two lanes and then braking abruptly, leading to a collision with another vehicle from the rear.

A video of the incident was posted by Facebook user KP Lau on March 30.

According to a time-stamp on the video, the incident occurred on March 26 at around 9.06pm, though it is unclear where it happened.

Three men can be seen exiting the car that was hit, as did the other party from his vehicle.

However, it is unclear what happened after the video, which has garnered over 111,000 views and 1,500 shares to date.

Stomp has reached out to KP Lau for more details.