Foul play is suspected in last week's fire at the old McReynolds High School in South Pittsburg, Tennessee, the city's Fire Chief Corey Comstock said.
He said it was determined there was no inclement weather to cause the fire that day, and no electricity was connected in the building.
The fire department, police department and sheriff's office were all on scene today collecting samples, Comstock said.
The Tennessee Bureau of Investigation is also assisting the investigation, TBI spokesman Josh Devine confirmed to the Times Free Press.
Investigators' next step is to confirm if any accelerants were used to aid the fire, Comstock said.
South Pittsburg police Chief Wayne Jordan asks anyone with information is asked to call the police department at 423-837-6115 or the Marion County Sheriff's Office at 423-942-3004.