Students arriving Monday at a small South Carolina high school faced newly installed metal detectors and extra security. This follows a student arrest for what authorities said was a plan to carry out a Columbine-inspired attack.

Bomb-sniffing dogs checked the hallways and classrooms at Chesterfield High School. Metal detectors were borrowed from a courthouse, and police met students at the doors.

The father of one 16-year-old sophomore said the police work over the weekend gave him confidence his son was safe. "I think they're pretty much on top of it. They've had plenty of time to find anything," said parent Michael Wattson.

The alleged plotter, Ryan Schallenberger, 18, was due in court Monday afternoon for a bond hearing. He was arrested Saturday after his parents called police, because 10 pounds of ammonium nitrate was delivered to their home in Chesterfield. Police also said they discovered a disturbing journal.

The teen was in the Chesterfield County jail Sunday night, charged with possessing materials to make bombs, the police chief said. Other than the bomb-making material, no other weapons were found at his home, Lear said.

The teen planned to make several bombs and had all the supplies needed to kill dozens, depending on where the devices were placed and whether they included shrapnel, Lear said. Ammonium nitrate was used in the Oklahoma City bombing in 1995 that killed 168 people.

Schallenberger also left an audio tape that was to be played after he died explaining why he wanted to bomb his school, authorities said. Lear wouldn't detail what was on the tape except to say Schallenberger was an angry young man.

Chesterfield is a town of about 1,500 people in northeastern South Carolina near the North Carolina line.