In all, 34 detonations were used to destroy the munitions, according to a news release from Raleigh police. Five of those happened today.

Meanwhile, local and federal investigators said three men were arrested in Sanford and Harnett County during the hunt for the metal scroungers who sold the munitions to the scrap dealer. It's unclear how the trio was involved in the case, as federal agents declined Friday to give any details about the investigation, but all three were charged with immigration violations.

Investigators declined to release the names of the three men. Capt. David Smith, a spokesman for the Sanford Police Department, said federal immigration agents had arrested two of them after his department's SWAT team located them while responding to a request from the Raleigh Police Department.

An ATF agent told the Associated Press Friday that a third man also was arrested during the investigation and charged with entering the United States illegally and with illegal possession of a firearm by a felon.

The live munitions, including more than two dozen anti-tank rounds, turned up in a load of scrap metal dropped of last week at the scrap yard. Some of the ammunition exploded on Tuesday, injuring two workers, as it was being compacted into bales for recycling.

How the scroungers got the munitions is still a mystery. An FBI spokeswoman in Charlotte said Friday that she couldn’t release any new information about the investigation.

Working from identification given to the scrap yard, investigators traced the explosives to Sanford.

The two men detained by the Sanford police said the munitions had come from the Fort Bragg area, said Smith of the Sanford Police Department. He declined to elaborate, saying he did not want to harm the ongoing federal investigation.

"That's what the suspects told us in the course of our involvement," he said. "They gave us specific information, but I can't go into that."

A spokesman for Fort Bragg, Tom McCollum, said Thursday that base officials had no idea whether the munitions had come from Bragg or how someone might have acquired them.

A Sanford police SWAT team found one of the men, along with spent shell casings and one live artillery round, at a home in the Carver Drive area in Sanford, Smith said. The second man was found in the Broadway area of Harnett County.

The fact that the live ammo was in a yard "makes me believe they just didn't know what they had," he said.

Today was the fourth day of detonations at the plant. Raleigh police closed a section of Garner Road near the company again today, and nearby residents once again had to evacuate. Residents will be allowed home tonight for good.

The concussive booms and evacuations have been a major disruption for those living near the largely industrial area just south of Raleigh's Beltline.

The company's CEO, Greg Brown, today thanked the city officials and the public for their patience with the situation. He said residents have been inconvenienced, adding "even they understsand this is for the betterment of all."

Brown, who owns another scrap metals facility in Goldsboro, reiterated today that the company doesn't knowingly accept hazardous material, including live ammunition. He said he had arranged for a retired Army colonel to help train workers at both the Goldsboro and Raleigh facilities on how to recognize live munitions.

Also this afternoon, City Manager Russell Allen said in response to a question that the situation had not created a financial burden for the city. "One of the things our taxpayers pay for is public safety," he said. "There have been no special extraordinary expenses above what we would expect."