At least two civilian employees were killed and three got injured when an armed U.S. Navy sailor opened fire before he fatally shot himself at the Pearl Harbor Naval Shipyard near Honolulu, Hawaii.

The injured are being treated at a local hospital.

According to the details, the shooter serves as an active sailor at USS Columbia.

However, it is still not clear that what sort of weapon the shooter carried when the attack was targeted.

Joint Base Pearl Harbor-Hickam said the situation began at 2:30 p.m. local time, and the base went on lockdown. The lockdown was lifted around 4 p.m.

One witness told that he was at his desk when he heard loud pops.

According to an official, investigation are underway to reveal the motive behind the attack.

An investigation was still being done as to the nature of the gun involved in the shooting. Personal weapons are not allowed on base, an official said.

Multiple service ambulances were sent to the scene and the Honolulu Fire responded with six units, including almost two dozen firefighters.

Base security and the Naval Criminal Investigative Service are currently investigating. The names will not be released until next of kin have been notified.