(CNN) -- A 37-year-old airline passenger was arrested Tuesday in Miami after primer caps for bullets ignited while a baggage handler was unloading a roll-on bag, the FBI said.
The tarmac incident is not believed to be terrorism-related, FBI special agent Michael Leverock said.
Leverock would not provide details or speculate on how the bag might have gotten on the plane. He compared the primer to a "spark plug" for the bullet.
The unidentified passenger, a naturalized U.S. citizen who was bound for Jamaica, was charged with transportation of hazardous materials. If convicted, he could face a sentence of up to five years.
The flight from Boston landed at Miami International Airport around 11:30 a.m., American Airlines said. The 737 had two pilots, four flight attendants and 148 passengers.
Hundreds of the primer caps were in a bag that ignited, and all of them went off after the first one did, Leverock said. Several hit the baggage handler's shoes, but he was not injured.
The bomb squad was among those who rushed to the scene.
The incident caused four other flights to be delayed, the airport said.
Leverock said part of a shirt inside the bag was charred, but the movement of the bag is what set off the explosion.
CNN's Sara Pratley contributed to this report.