Chemical weapons incinerators at the Pine Bluff Arsenal remained shut down Monday after a fire broke out in an explosion containment room Sunday morning.

The fire was quickly extinguished and the remaining 35 rockets filled with nerve agent that were already in line to be processed were sent through the incinerators Sunday evening. But the incinerators were then shut off and remained idle Monday as crews tried to determine what caused the fire.

"We haven’t returned to full-scale operations," arsenal spokesman Raini Wright said Monday.

Wright said she didn’t know when crews would resume destroying the massive store of chemical weapons at the Pine Bluff Arsenal. The Jefferson County facility houses 12 percent of the nation’s chemical weapons stockpile.

Sunday’s fire began when a rocket containing GB nerve agent ignited as it was being cut into pieces to be more easily incinerated. The sheared rocket ignited and burned for 20 seconds before being put out.

No nerve agent escaped from the airtight facility and no equipment was damaged, according to a news release sent out Monday by arsenal officials.

Sunday’s fire marked the third time in two weeks that work was stopped at the arsenal. A similar fire May 11 shut down operations for two days. Last week, operations shut down again because of concerns over a fire that broke out at a similar facility in Umatilla, Ore