A witness told the FBI the youths appeared to be about 14 or 15 and wore clothes common to the "goth" youth subculture: baggy black pants with silver chains, Converse sneakers and black T-shirts with gray writing. Both had purple makeup around their eyes, FBI spokeswoman Carol Michalik said.

The male teen was described as 5 feet 10 inches, about 200 pounds, with a medium build and short, black, curly hair. The female is 5-8, about 200 pounds, with black, shoulder-length, frizzy hair and a pink-dyed stripe.

CSX is offering a $5,000 reward for information that leads to an arrest and conviction.

The train's lead engine derailed and flipped onto its side July 30 on Busch Boulevard after it struck a piece of equipment on the track. It landed near an office building and forced officials to close a stretch of Busch Boulevard.

The piece placed on the track, known as a knuckle, is part of the coupling mechanism that connects train cars. They frequently break off and are left by train workers by the side of the track. But workers would never have left a knuckle, which weighs about 50 pounds, on the track itself, Michalik said.

Anyone with information in the case is asked to call the FBI at 813 253-1000.