An internal investigation board and an outside firm will both try to determine what caused a fire that destroyed a warehouse and some 7,500 containers of white phosphorus earlier this week at the Pine Bluff Arsenal, officials said Wednesday.

The fire was discovered by security guards shortly after midnight on Monday. It was brought under control by 1 a.m. and burned itself out by 5 p.m. on Monday. No one was injured.

The arsenal’s investigation board will include experts from the U.S. Army Chemical Materials Agency. Mark Lumpkin, director of risk management and regulatory affairs, will serve as the board president, according to a news release from the arsenal.

Fire Cause Investigations, a division of System Engineering Laboratories Corp., of Houston, will conduct an independent investigation, arsenal officials said.

White phosphorus is used in ammunition and to generate smoke screens. The Pine Bluff Arsenal is the Army’s sole producer of white phosphorus ammunition in the western hemisphere.

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, Lt. Col. Searless Hathaway said in the prepared statement.

The warehouse, near the Warbritton Gate, was not involved in chemical weapons disposal.

This story was published Thursday, June 9, 2005.