Jason Derulo -- Booted From Flight After Airport Shouting Match

4:14 P.M. PST -- A rep for Jason tells TMZ the singer requested an escort to get him and his crew through the airport faster because TSA precheck was down ... they were refused.

When they called "bulls**t" ... the rep says airport staff refused to let Jason's crew get on the flight, but she says Jason was allowed on. It appears other members of his crew got on as well, and that's why airport cops came and escorted them all off. We're told he's currently on a private jet to make it to his show in LA tonight and they're extremely upset with the way Southwest Airlines handled the situation.

Jason Derulo and his crew were booted from a flight Saturday after he and his bodyguard got into it with an airport employee ... eyewitnesses tell TMZ.

We're told Derulo was traveling from Reno to L.A. when one of his bodyguards was denied preferred boarding ... one eyewitness says he wanted TSA precheck but for some reason didn't get it.

According to eyewitnesses, Derulo and his team got pissed and started shouting at an airport employee.

One eyewitness says an employee from the airline told Derulo and crew they would not be allowed to take the flight, but they went through security anyway.