Investigators have still not determined the cause of the fire Sunday at the old Robbins mill.

The federal Bureau of Alcohol, Tobacco, Firearms and Explosives National Response Team worked with the State Bureau of Investigation and the Robbins Fire and Police departments until Thursday trying to figure out what caused the massive blaze.

Carl Vasilko, ATF special agent in charge, said the National Response Team concluded its part of the investigation Thursday and left town. The Charlotte Field Division of the ATF and local investigators are continuing the investigation.

"The ATF team -- the National Response Team -- has completed our work here," Vasilko said. "The status of the fire is currently ruled undetermined, but remains under investigation."

Because the investigation was still going on, Vasilko said that was all he was permitted to say at this point.

The fire damaged between 60 and 70 percent of the 300,000-square-foot mill, according to the county.

The National Response Team is a group of arson investigators from all over the country who come together to work large fires, Vasilko said. The team has been in existence since 1978.

It deployed to the Pentagon in 2001 to investigate the 9/11 terrorist attack. It also works at major sporting events, presidential inaugurations and national political conventions.

This is the fourth time in the last 14 months that the team has responded to a fire in the Carolinas, according to the ATF press release.

Vasilko would not reveal if there was anything suspicious about the fire and said that residents should not read anything into the team's presence.

"It's not uncommon," he said Tuesday. "These are the types of fires we do respond to. Anything of this size requires a lot of resources. It would not be unusual for us to be here investigating, whether there are suspicious factors or not."

The team brought an array of resources that might be otherwise unavailable for local investigators. Members of the team include chemists, electrical engineers and accelerant-detecting dogs.

Investigating the mill fire had some added difficulty because it required moving some heavy debris, Vasilko said. Much of the rear of the building is completely destroyed and remains a mess of twisted metal and brick.

According to an ATF press release, early estimates of the damage to the former Milliken plant are more than $1 million.

Firefighters from each department in Moore County and some from four other counties fought the fire through the day Sunday and on into Monday morning.

EVH Supply Co. of Randleman had bought the building in January. Residents had seen workers salvaging materials from the building.

Contact Matthew Moriarty at 693-2479 or by e-mail at moriarty@thepilot.com.