Investigators said it began around 9:20 a.m. when they got a 911 call about a possible drunk driver driving a Ford Focus on Old Coats Road.
Officers found a Ford Focus parked at an abandoned home on Old Coats Road and approached it.
They said the driver, 24-year-old Ryan James Gibson, showed them a gun and threatened to kill himself.
Officers backed off and began negotiating with Gibson. During the conversation, Gibson told them he had a grenade at his home in Garner.
Officers said they talked with Gibson for three hours, but he eventually shot and killed himself.
Harnett deputies contacted the Garner Police Department about the grenade threat.
About 30-40 units were cleared in the Abberly Place Apartment Homes in the 500 block of Abberly Crest Boulevard. That's near the intersection of I-40 and Highway 70.
At about 5:30 p.m., officials said no device was found and they began allowing residents to return to their homes.