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ST. GEORGE, Utah — A teenage student at a southern Utah high school has been charged with bringing a homemade bomb to the school that was discovered in a backpack emitting smoke and prompted an evacuation, police said Tuesday.

The boy was arrested Monday night after Pine View High School in the city of St. George was evacuated for two hours that afternoon while the FBI and a bomb squad investigated. Police declined to identify the arrested teen or give his age.

Authorities said additional charges also are pending against the teen as a suspect in the raising of the Islamic State group's flag on a pole at another Utah high school last month just after the Florida mass school shooting that was followed by numerous other threats to schools around the U.S.

No one was hurt Monday after the backpack was found in a common area of the school by a student who reported it to a teacher.

The boy was arrested and booked into a detention center on charges of manufacture, possession, sale, use or attempted use of a weapon of mass destruction, St. George police said in a statement.

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No one was hurt, no damage was reported and the school reopened Tuesday morning for classes. Police did not describe the homemade bomb in detail but said it "had the potential to cause significant injury or death."

"Based on our investigation we can confirm this was a failed attempt to detonate a homemade explosive at the school. It was also determined that the male had been researching information and expressing interest in ISIS and promoting the organization," police said.

Police in the city of Hurricane about a half-hour drive from St. George said Tuesday the teen who was arrested is also suspected of raising an Islamic State group flag in February at Hurricane High School. That happened on Feb. 15, a day after a mass shooting at a school in Florida. Authorities initially thought the graffiti and flag at the school were pranks.

The backpack at Pine View High School was found by a student who reported to a teacher that smoke was coming out of it shortly after noon Monday, said St. George Police Capt. Giles said.

The teen who was arrested was attending class at the school and items were seized from his home "that were consistent with the material used to build the device placed at Pine View," St. George police said.

Hurricane Police officer Ken Thompson confirmed "charges are pending on our incident here with the flag."

"When the search warrant was executed, there was evidence taken from the house that tied him to our case," he told The Associated Press Tuesday afternoon.

School District spokesman Steve Dunham said the school with about 1,100 students hadn't experienced any similar incidents in recent years.

"I think it is a shock to all of us that something like this has happened in one of our schools," he said.

In the case at Hurricane High School, the U.S. flag was found on the ground and slashed with a flag with Arabic letters waving from the flagpole.

The FBI analyzed an image of the flag that had been raised and agents determined the group was not involved, Thompson said earlier.