An 18-year-old Japanese student preparing to board a plane to Tokyo was arrested on Sunday after a search of his baggage turned up hidden weapons and explosives, police said.

Yoshio Kosugi, a student at Drexel University in Philadelphia, was carrying a Japanese passport and ticket to Tokyo. He was detained while trying to check in at the last minute for a Northwest Airlines morning flight.Police found a dismantled rifle, dummy hand grenades, a pellet gun with carbon dioxide cartridges and explosive black powder in Kosugi's bagage, according to police Capt. Stanley Puchalski.