Giovanni Joe Akima, 28, has been arrested on suspicion of terrorizing at the Guam Housing and Urban Renewal Authority main office in Sinajana on Wednesday.
The incident temporarily shut down the agency.
Shortly before noon, an incident occurred between an unnamed GHURA employee and Akima, according to Guam Police Department spokesman Sgt. Paul Tapao.
Akima wanted to speak to the GHURA employee concerning a car parked in the employee's parking lot.
Police alleged Akima brandished a pocket knife and asked the employee to fight, and brandished what was initially thought to be a handgun as he left the area.
Akima later returned to GHURA and police were able to detain him.
"The handgun was later determined to be a pellet gun and was confiscated by officers at the scene," police stated in a news release.
Akima was arrested on suspicion of terrorizing, terroristic conduct, reckless conduct, resisting arrest, family violence and violation of a court order.
Police forwarded the case to the Office of the Attorney General for prosecution.