KING

An Oregon college went into lockdown this week, when a student arrived at school wearing an ammunition belt.

SEATTLE - Increased tension since Monday's Virginia Tech shootings have prompted scares at numerous schools in Washington and across the Pacific Northwest.

The alarms occurred as many schools such as Pacific Lutheran University held ceremonies to remember the 32 victims at Virginia Tech, and just days before the April 20 anniversary of shootings at Columbine High School in Littleton, Colo.

Seattle police chief Gil Kerlikowske says his force is on "heightened alert" this week.

On Thursday, Todd Beamer High School in Federal Way was in lockdown for about an hour after police arrested a student and found three weapons. The student was discovered after a classmate sent a text message to their parent about the gun, according to Diane Turner, chief communications officer for the Federal Way district. No one was injured.

On that same day, Seattle police responded to a report of an 18-year-old student with a gun at West Seattle High School. The student had a BB gun, a police spokesperson told KING 5, and it wasn't clear if he'd threatened anyone with it.

In Tacoma, police arrested a 13-year-old boy Thursday after reports that he threatened to shoot a gun at Hunt Middle School. The boy was booked into Remann Hall juvenile jail on suspicious of malicious harassment.

Seattle police responded to a false threat at the University of Washington Thursday, when a caller reported sighting a gunman on campus. Police found it was only an ROTC drill and the caller had seen an ROTC student in fatigues, carrying a rubber rifle.

At Washington State University in Pullman, officials are considering installing a siren to alert students in case of an emergency, the Associated Press reports. The siren would be part of a system that includes mass phone call and e-mail alerts, and would be in affect at WSU branch campuses.

The school's Vancouver branch campus was evacuated earlier this week when graffiti was discovered in restrooms that threatened harm similar to the Virginia slayings.

Finally, an Oregon college went into lockdown Wednesday, when a student arrived at school wearing an ammunition belt. Authorities found the student, at Lewis and Clark College, did not have a weapon. The belt held only spent cartridges and the student wore it as a fashion accessory.

The scare touched as far away as Michigan Thursday, where officials at Kalamazoo Valley Community College closed the campus for the rest of the week because of a threat posted on an Internet blog.

The Associated Press contributed to this report