The Federal Aviation Administration says an unruly passenger went for the door, trying to get it open.
A passenger on the flight says other passengers stopped the man.
"Three men restrained him and prevented him from opening the door," Matthew Hughes of Galveston said. "If it wasn't for them, I probably wouldn't be here talking to you today."
Police took the unruly passenger into custody and the flight ended up heading on to Chicago.
Airport police and the FBI are questioning the man. No charges have been filed.
Aviation experts say it's impossible to open the door during a flight because of cabin pressure.