A man was stopped by TSA at Pennsylvania's Lehigh Valley International Airport trying to bring an explosive device on a plane Monday, the agency confirmed.

An official familiar with the investigation told ABC News the explosive was concealed in a checked piece of luggage and contained multiple fuses.

The passenger is now in FBI custody.

The passenger was set to take an Allegiant flight from eastern Pennsylvania to Sanford, Florida.

An airport spokesperson said the suspicious package was discovered shortly after 11 a.m. Monday and the west side of the airport's main terminal was shut down "for precautionary measures."

The package was removed from the airport and the closed portion of the terminal reopened shortly before 2 p.m., the spokesperson said.

This is a developing story. Please check back for updates.