The pilot of a Southwest Airlines flight from Fort Lauderdale, Fla. declared an in-flight emergency before landing at Baltimore-Washington Thurgood Marshall International Airport Wednesday night, the airline said. An airline spokesperson said a passenger set off a smoke detector while smoking an e-cigarette in the forward lavatory of Flight 3654. The pilot declared an emergency and landed the Boeing 737 safely at the airport. None of the 118 passengers and five crew members were injured. Fire department and law enforcement investigators determined the vapor from the e-cigarette set off the alarm.