The agency said investigators from the F.B.I., the Victoria fire marshal and the Department of Public Safety had classified the fire as “incendiary,” or intentionally set.
Nicole Strong, a spokeswoman for the A.T.F., said in a telephone interview on Thursday that the “incendiary” designation meant it was a “criminal act of arson.”
“The thing is, we don’t have anybody in custody,” she added. “We don’t know the motive of the person who did it. At this point, there is no evidence of a hate crime, but that could change if anything surfaces.”