According to a criminal complaint, federal investigators have accused a 40-year-old man of concealing an explosive device in a luggage at Lehigh Valley International Airport in Pennsylvania this week. Mark Muffley is in the custody of the FBI after checking his rolling luggage at a Pennsylvania airport on Monday morning in preparation for a journey to Florida with Allegiant.

The Transportation Security Administration detected an alarm while screening his backpack, according to the criminal complaint. The lawsuit states that agents investigating the bag discovered a plastic-wrapped circular device with a fuse and a granular-type powder “compatible with a commercial-grade firework” concealed in the case’s liner.

The material was flammable and “presented a major threat to the airplane and passengers,” according to the FBI. According to the allegation, surveillance footage recorded Muffley leaving the airport five minutes after he was summoned over the terminal’s public address system. On Monday night, he was arrested at his residence and charged with possessing an explosive at an airport and possessing or attempting to set an explosive device on an aircraft.