As many as 300 people had to be evacuated from a Kalihi apartment building on Sunday after nearly 40 pipe bombs were discovered inside one of the building's units, according to a Honolulu Police Department spokesperson.
Relatives cleaning out the apartment found several grenades in addition to the 36 other explosives, authorities said Monday.
Officials evacuated the six-story Pohaku Street building about 1:30 p.m. on Sunday. Officials confirmed they were working to dispose of the explosives found in a unit.
Officials believe the apartment belonged to someone who used to be in the military. Details on the man's background were not immediately released.
The evacuation order was lifted about 7:30 p.m., some seven hours after residents were told to leave their homes.
The Honolulu Police Department's bomb squad and SWAT team responded to the call, as did FBI agents and ATF officials.
Protacio Sapanza, the apartment's resident manager, told Hawaii News Now that relatives of the apartment's owner were cleaning it out when they found what they described as a "weapons cache." Sapanza called the former resident of the apartment a "loner."
Relatives called 911 immediately after making the discovery, neighbors said.
"The officer told everybody, 'Get out of the building,'" Sapanza said. "Right away, I knocked on everyone's door."
The American Red Cross of Hawaii opened a shelter at Lanakila Elementary School for evacuees.
Some 52 people came to the shelter, which closed at about 7:45 p.m.