High temperatures caused some of the remaining white phosphorus in the burned-out remains of a warehouse at the Pine Bluff Arsenal to reignite Thursday, officials said.

The fire is expected to flare up and die down as the investigation continues, Assistant Fire Chief Thomas J. Braumuller said at a news conference Thursday afternoon. The fire was expected to die down by early evening.

Braumuller said white phosphorus liquefies and ignites at 90 degrees Fahrenheit.

The initial fire was discovered by security guards early Monday morning. It was brought under control by 1 a.m. and was believed to have burned itself out by 5 p.m. before flaring up again around 1:30 p.m. Thursday. No one was injured in either incident.

An internal investigation board and an outside firm are trying to determine what caused the fire that destroyed the warehouse, which contained about 7,500 containers of white phosphorus used in the manufacture of ammunition and to generate smoke screens. The Pine Bluff Arsenal is the Army’s sole producer of white phosphorus ammunition in the western hemisphere.

The warehouse, near the Warbritton Gate, was not part of the ongoing work to dispose of the arsenal’s chemical weapons stockpile.

On Thursday, investigators were standing on an elevated platform above the remains of the warehouse when the fire reignited, Braumuller said. Firefighters, who’ve been on the scene since Monday, immediately sprayed water in front of the platform, and the investigators quickly left.

At a truncated news conference Thursday, officials showed video footage of the building’s remains before answering a few questions and heading back to the scene.

The video showed that a burned-out hull and debris from the canisters are all that remain of the warehouse. The thick white smoke pouring from the center of the remains resembled the white clouds produced by smoke machines.

Lt. Col. Searless Hathaway said some workers had gathered outside the main gate Thursday to get away from the smoke. "We did not call for an evacuation," said Hathaway, acting commander of the arsenal.

Prolonged exposure to the smoke can irritate the eyes, skin and nose. Results of water and air samples taken in the surrounding area are pending.

Anyone with prolonged symptoms from the smoke should seek medical attention, arsenal officials have said.

This story was published Friday, June 10, 2005.