Raleigh, N.C. — Local and federal authorities continued Wednesday night to track down the source of the munitions at a Raleigh scrap metals plant.

Neighbors who were evacuated as a safety precaution were allowed to return for the night Wednesday, but police said they would have to be out again by 8 a.m. Thursday, spokesman Jim Sughrue said.

“We were frustrated because by the simple fact, we couldn't grab nothing, we just had to leave,” evacuee Sherman Dunston said as she described the first evacuation.

Two explosions were reported Tuesday morning at Raleigh Metals Recycling, at 2310 Garner Road. Police and experts from Fort Bragg determined unexploded ordnance got mixed into a batch of scrap metal being processed at the plant.

The Army team determined late Tuesday that more munitions were in the scrap heaps, and they decided that detonating them at the plant was safer than moving them elsewhere for disposal.

Maj. Mark Carruso, of the 57th Ordnance Group from Fort Gillem in Forest Park, Ga., who is helping clear the plant, said three 90 mm rifle rounds and 18 anti-tank projectiles were found in the bales of scrap metal. The devices didn't have fuses, so they posed no risk to the public, aside from the plant workers, he said.

"The Army, as a whole, has pretty stringent procedures for accounting for ammunition, from the time you draw it out of your ammunition supply point to when you use it to when you turn it in," Carruso said. "So, to have something like this is very unusual."

Eighteen of the devices had been detonated by Wednesday evening. The soldiers were expected to stop the process for the night.

Plant owner Greg Brown said Wednesday morning that authorities know who brought the munitions to the plant.

The person, whom Brown didn't identify, sold a load of scrap metal to the plant last Thursday, he said. Workers sifted through the materials and saw the shells, but didn't recognize them as live ammunition, he said.

"I don't know how they were not viewed as munitions," he said, adding that his workers "clearly need reinforced training."

Raleigh Metals Recycling has a policy against accepting ammunition and other hazardous materials, such as flammable liquids or oxygen containers, Brown said.

"We get things from the military," he said. "We do get some spent shells, (but) no live ammunition."

The person who sold the munitions to the plant is a repeat customer who has never brought in anything like that, he said.

Brown said he has turned the person's driver's license number and other information over to authorities. Raleigh Police Department investigators and agents with the FBI and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives are investigating the case.

State Department of Labor investigators also plan to review the incident but have to wait until the military finishes detonating the ordnance.

The force of the initial explosion Tuesday knocked over one worker, and a second worker complained of ringing in his ears. Isai Bravo Santiago, 33, was treated at WakeMed and released, while Adrian Bravo, 27, was listed in good condition at the hospital Wednesday morning.

Brown said the design of the plant, which is open on three sides, diffused  the force of the explosion, limiting the injuries and the physical damage to the plant. The explosion did blow a hole through the plant's corrugated metal roof.

Garner Road will remain closed to through traffic between Rush Street on the south and Newcombe Road on the north. Drivers are advised to use alternate routes.

The Garner Road YMCA, located across from the plant, also is closed, officials said.

Police notified people living within a one-mile radius of the plant of the detonations and briefly closed a section of the Interstate 440 Beltline Tuesday night.

As a precaution, police also evacuated the Biltmore Hills Apartments across from the plant Tuesday night. The American Red Cross opened a shelter at Garner United Methodist Church for residents, and six people spent the night there Tuesday.

Wayne Nordan who lives off Lake Wheeler Road, about 2 miles from the detonation site, also evacuated.

“I was on the phone with my sister. It sounded like someone pounding on the awning. It just shook, everything shook,” Nordan said.

Neighbors said the repeated detonations Tuesday night and throughout the day Wednesday put them on edge.

"It's just like being in Iraq or something," neighbor Charlie Simmons said.

"Suppose all of (the munitions) had gone off at the same time – now that could have been scary," neighbor Maureen Smith said.

The shelter was expected to remain open at least through Wednesday night, officials said.

Raleigh City officials said they believe the cost of the Raleigh Metals Recycline incident will be minimal. Raleigh Mayor Charles Meeker said the city trains for emergencies like this and it has the personnel to respond.

“We have 700 police officers, likewise for firefighters,” Meeker said.