Yokota Air Base officials are punishing four students for their roles in Yokota Middle School’s bomb threat incidents earlier this year.

In a written statement to Stars and Stripes, Col. Kenneth Wavering, the 374th Airlift Wing and base vice commander, said four middle school students “have admitted to placing the notes during the two bomb threats at the middle school.”

The school was evacuated March 29 after the discovery of two notes threatening a bomb. Military officials declined to disclose the notes’ contents.

Two of the students have been debarred from base and the other two are in the process of being debarred, Wavering said. All four were expelled from school.

Base officials previously said that anyone expelled from base would forfeit their Status of Forces Agreement privileges and have 30 days to either leave Japan or apply for a visa as a foreign national.

“We are not vindictive towards these students but our intent is to provide a safe environment for all Yokota members to live and work,” Wavering wrote. “Bomb threats not only disrupt our daily activities but have the potential for seriously injuring people during evacuations as well as tying up all our emergency services.”

Yokota’s community has been rocked by four bomb scares this year, including two at Yokota High School.

“We have yet to identify the people who placed the threats at the high school,” he said in the statement, “but we have learned a great deal so far and are getting close to identifying suspects.”

Military officials found and punished the author of a bomb threat note found on base. In a March 24 nonjudicial hearing, a staff sergeant was reduced in rank to senior airman and given 45 days of extra duty and a reprimand.