Elphbert Laforteza, a senior, was booked into jail Friday night, hours after the bottle-bombs went off in trash barrels during lunch.
He will be released from custody pending further investigation, said spokesman Paul Levikow of the San Diego County District Attorney's Office.
More arrests are anticipated and charges could be brought at a later date, Levikow said.
Besides the five crude homemade chemical bombs that exploded, three others were disabled by the bomb squad and officers found four others partially assembled in Laforteza's backpack, according to authorities.
Nobody was injured and no property was damaged in the explosions.
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.
Laforteza was an all-league football player and an ROTC cadet. He had applied but had not been admitted to the Air Force Academy, a spokesman for the Air Force said.
San Ysidro High Principal Hector Espinoza said Laforteza will receive his diploma but will not be allowed to graduate with his class on Thursday.
Waterfront Park in downtown San Diego played host to thousands of people demonstrating in the third annual Women's March, which also took place in dozens of other cities across the country.
Three people robbed a San Carlos jewelry store on Saturday afternoon, then fled before officers were able to arrive, police said.
A record number of County employees will be hitting the streets next week to help count homeless people in the region.
People choosing not to vaccinate are now a "global health threat," according to the World Health Organization.
As the state’s affordable housing crisis worsens, the City of Encinitas has launched a bold new initiative to encourage its homeowners to do their part.