Four people - including a police officer - have been left injured after a suspected stabbing incident at Engadine in southern Sydney on Sunday morning.
A major police operation is under way and paramedics are treating multiple victims after emergency services raced to a two-vehicle crash at Old Bush Road and the Princes Highway.
After multiple 000 calls, the first officers to arrive on the scene found a man with stab wounds.
Police said he allegedly ran from the scene before he was tasered and taken into custody.
During the arrest, a male police officer suffered a serious laceration to his left wrist.
A woman, a passenger in one of the vehicles, was also treated for stab wounds.
A fourth person was also injured and police said it was unclear what their involvement in the incident was.
All four people were treated by paramedics at the scene.
The Princes Highway has been closed in both directions and motorists are being urged to avoid the area.