SAN DIEGO -- A student set off 12 crude homemade chemical bombs in trash cans at San Ysidro High School Friday afternoon, prompting an hourlong lockdown at the campus but causing no injuries or property damage, authorities said.

The 18-year-old senior who planted the makeshift explosive devices -- plastic bottles containing some type of acid and another unidentified substance -- was under arrest within an hour of the explosions, which occurred about 3:15 p.m. in a patio area, according to San Diego police and fire officials.

10News has confirmed that Senior Honor Student, Elphbert Laforteza, was arrested.

He is expected to face felony charges of detonating explosives and possessing bomb-making materials, authorities said.

Laforteza was booked at the county jail on 5 counts of making a destructive device and 8 counts of use of an explosive device to injure.

Laforteza told investigators he had brought a dozen of the bottle bombs to the Airway Road campus, said Maurice Luque, a spokesman for the San Diego Fire-Rescue Department. Six detonated, and authorities found and confiscated six others that either had not been fully assembled or were complete but failed to blow up for some reason.

Although Laforteza told school officials he considered the episode nothing more than a senior prank, authorities noted that such devices are highly dangerous as well as illegal.

"They can kill you," Luque said.

School officials said although Laforteza will receive his diploma next week, he will not be allowed to graduate with the rest of his class.