Peel Regional Police say one man is in custody after a fight broke out in Brampton on Sunday afternoon.
Officers were called to the area of Newhaven Manor and North Park Drive just before 12:45 p.m.
Two men were located with injuries and transported to a trauma centre.
One of the men was in life-threatening condition and the other in non-life threatening condition, paramedics said.
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Police say witnesses saw a knife but are not able to confirm at this time.
Police did not say what may have led to the incident.
Peel Regional Police are asking anyone with information to contact police.