Alexander Youshock, 18, is charged in San Mateo County Superior Court with attempted murder and other felony charges for the Aug. 24 incident at Hillsdale High School, prosecutors said.
A grand jury returned the indictment against Youshock on Friday after a four-day grand jury hearing, Chief Deputy District Attorney Steve Wagstaffe said.
He is charged with two counts of attempted murder, two counts of exploding a destructive device with intent to commit murder, one count of possession of a destructive device in a public place, one count of use of explosives in an act of terrorism, and two counts of possession of a deadly weapon.
Wagstaffe said the district attorney's office decided to bring the case before a grand jury rather than hold a preliminary hearing in order to speed up the court proceedings.
Youshock's defense attorney, Jonathan McDougall, has suggested his client might not be competent to stand trial, and three doctors have been appointed to evaluate his competency.
The first two doctors have disagreed on whether he can stand trial, and the third doctor's report, due June 3, is expected to be the deciding opinion.
The grand jury indictment means that if and when Youshock is found competent to stand trial, the case can immediately proceed to setting a trial date as opposed to having to go through a preliminary hearing, Wagstaffe said.
Youshock has been in custody without bail since he was arrested the morning of the pipe bomb incident. He is being charged as an adult even though he was 17 when he allegedly brought the pipe bombs to school.
Police said Youshock set off two pipe bombs inside a hallway at the high school shortly after 8 a.m. He is also suspected of bringing a chainsaw, a 2-foot sword and eight more pipe bombs onto the campus.
He was arrested after being tackled by a teacher who, along with the school's principal and several other school employees, was hailed a hero afterward.
Youshock's will be arraigned in San Mateo County Superior Court on the grand jury indictment at 8:30 a.m. Tuesday.