Man stabbed during walk in western Sydney

A man has been stabbed while walking near a lake in western Sydney before escaping to a fast-food restaurant to get help.

The 24-year-old was walking at Lake Woodcroft in Blacktown about 5am on Monday when he was approached by three men, NSW Police said in a statement.

Detectives said one of the men produced a knife and threatened the victim before stabbing him four times in the back and robbing him.

The trio fled and the victim managed to get to a nearby takeaway restaurant where he was met by police and paramedics.

The man was taken to Westmead Hospital in a serious condition. Police are hunting for the three assailants.