CHICAGO (CBS) — A Southwest Airlines flight returned to Austin on Tuesday after taking off for Chicago, when one passenger began punching another.

Flight 3590 to Midway International Airport already had been delayed about 90 minutes, and 30 minutes after takeoff, there was an altercation between two passengers.

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“I think one of the guys was drunk,” said fellow passenger Oren Stewart.

According to Stewart, that man reached over and punched another passenger, for no apparent reason.

Another passenger, Lisa Birkman, said flight attendants separated the two, who apparently did not know each other.

“We heard some loud noises, like in the back of the plane. The flight attendant was making one of the passengers move, and then a few minutes later the captain came on and said that we had to turn around and go back to Austin,” she said.

Stewart said the passenger who appeared to be drunk also was staring at a woman, making her uncomfortable. He appeared to be smiling as police escorted him off the plane.

Two passengers were escorted off the plane when it returned to Austin. The flight finally arrived in Chicago six hours late Tuesday night.

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Charges were pending against one of the passengers who was removed from the flight.