Bryce A. Reed, 31, is accused of possessing materials that can be used to make a pipe bomb, U.S. prosecutors said.
Investigators would not say if Reed -- arrested Thursday by agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives -- is a suspect in the fire and explosion April 17 at West Fertilizer Co. that killed 15 people and devastated the small town of West.
The Texas Department of Public Safety said Friday a criminal investigation into the blast is under way.
"We want to ensure that no stone goes unturned and that all the facts related to this incident are uncovered," Public Safety Director Steven McCraw said in a statement.
McCraw said the Texas Rangers will join McLennan County Sheriff Parnell McNamara in the investigation.
"The citizens of McLennan County and Texas must have confidence that this incident has been looked at from every angle and professionally handled -- they deserve nothing less," said McNamara.
The state fire marshal says weather, natural causes, anhydrous ammonium and ammonium nitrate in a trail car have been ruled out as causes, CNN reported.
A criminal complaint released Friday says Reed gave an assortment of bomb-making components to a friend April 26. The friend notified authorities after he opened the box and saw what appeared to be a pipe bomb, The Dallas Morning News reported.
Reed was charged Friday with possession of a destructive device. He did not enter a plea, the newspaper said.
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