Amid heightened fears over campus safety since last week’s murderous shooting rampage at Virginia Tech, three more colleges on Tuesday were the scenes of disruptive threats.

A 53-year-old student at San Francisco City College was arrested after he stood up in a physics class and started “screaming that he was going to kill everybody,” a police officer told The Examiner, a local newspaper. The student, Peter Lee, was dressed in camouflage but was not armed. Mindful of what had happened at Virginia Tech, however, professors in nearby classrooms locked their doors and told students to take cover. Mr. Lee was charged with making terroristic threats. The college’s chancellor, Philip Day Jr., said it was compiling a list of students considered to be risks for disruptions.

“If there was ever a doubt after the Virginia Tech situation that this could happen to us, that doubt has now been cast aside,” Mr. Day told the newspaper.

The Rock Creek campus of Portland Community College, in Oregon, was shut down on Tuesday and remains closed today after a threatening note was discovered in a bathroom, according to Salem-News.com, a local-news Web site. The note promised a repetition today on the Rock Creek campus of the Virginia Tech shootings.

Skagit Valley College, in Mount Vernon, Wash., was evacuated and closed after it received a telephone threat of a shooting, the Associated Press reported. According to the college’s Web site, it plans to open on time today. —Andrew Mytelka