School buses. (iStock)

A 15-year-old student in Phoenix was taken into custody Tuesday after a classmate saw him carrying “several pounds” of potassium nitrate, according to Phoenix Police Sgt. Tommy Thompson.

The incident took place at Pinnacle High School, where the teenager was detained one day after the same classmate overheard him saying he wanted to “blow up a Muslim church,” Thompson said. The classmate reported the comment to his parents Monday evening, but told police he didn’t see any weapons or devices “to show he had the means to carry out what he was saying.”

On Tuesday, however, the reporting classmate went directly to school officials after he saw the teenager with a plastic bag full of white power. Police were called, and a bomb squad determined the bag contained potassium nitrate — a saltlike substance that can be mixed with other chemicals to create flash powder, Thompson said.

“In and of itself it’s not a hazard, but you mix it with other chemicals, you can ignite it with a fuse,” Thompson said, adding that it can be ordered through the mail.

The bag was reportedly labeled “potassium nitrate,” Thompson added.

Thompson said the student did not make any direct threats against Pinnacle High or anyone connected to school. He also didn’t name a specific Muslim facility in his apparent threat, which police are continuing to investigate.

The student remained in police custody Tuesday night.

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