Suspicious powder on plane at PBIA November 16, 2011 at 10:45 PM EST - Updated June 25 at 10:26 PM WEST PALM BEACH, FL (WFLX) - Passengers and crew of a Southwest jet were evacuated Wednesday afternoon at Palm Beach International Airport after the discovery of a mysterious powder. A flight attendant found the suspicious substance in a tissue box. Fire rescue said the plane was Southwest flight 793 to Baltimore. The plane was scheduled to take off at 4:10 p.m. 137 passengers are waiting on the tarmac as the plane is inspected. Chairs have been brought out for their comfort. A HazMat crew is suiting up to inspect the plane. Two crew members were exposed to the substance, according to West Palm Beach spokesman Chase Scott. They are still on the plane waiting for decontamination. Vehicle traffic around the airport has not been affected. The airport remains open and other flights are arriving. Copyright 2011 WFLX. All Rights Reserved.