A young man from Crosland Moor was stabbed twice after being attacked in the street.
Police taped off a large area of the pavement along Dryclough Road and Cromarty Drive where the incident took place.
West Yorkshire Duty Police Inspector Graham Hawcraft said: "We were called out at 7.02pm after reports that a 20-year-old man had received a couple of stab wounds.
"He was taken to hospital by ambulance."
Mr Hawcraft said it was too early to say how seriously he had been hurt.
At least a dozen officers secured the scene while other officers conducted a search by torchlight in the gathering gloom.
Retired postal worker Neil Brook, 68, who lives on Dryclough Road said: "I just went out to walk my dog Oscar and much of the street was sealed off.
"At first I thought perhaps there had been a motorbike accident, I hope the injured young man is Okay and pulls through."