CHICAGO -- An investigation is underway after a man was stabbed during a fight outside Chicago's O'Hare International Airport.
The incident happened around 1 a.m. Wednesday on the pedestrian bridge between Terminal 5 and the parking lot.
Police said the men, who are known for soliciting passengers, got into a verbal argument on the lower level of Terminal 5.
The city says they are not licensed Chicago cab drivers.
"They are pirate operators that troll for rides in places where no legitimate drivers would ever be allowed," the city said in a statement. "They are unlicensed operators."
The argument continued up the escalator heading to parking lot D, when one of the men swung a safety cone at the other. That's when the other man pulled out a knife and stabbed the other in the stomach.
An officer working at O'Hare saw the altercation and called for back-up.
The victim was taken to the hospital in serious to critical condition.
Police said the suspect was arrested. Chicago Police have indicated that he will be charged with Aggravated Battery with a weapon.
The pedestrian bridge was closed for three hours overnight as police investigated.
No passengers or airport employees were involved in this incident.
This is a developing story. Check back for details.