A bomb threat scrawled on a bathroom wall at Columbia Falls Junior High School was taken seriously enough by school officials to have an explosive-sniffing dog and its handling team brought in to search the school Thursday night.

No bomb was found and school was open normally on Friday.

The graffitti, which included a threat of a bomb going off on Friday, was discovered Monday evening.

School staff evaluated the seriousness of the threat and made arrangements for professional bomb-detection personnel to come to the school, which took several days, junior high Principal Dave Wick said.

Parents were notified about the threat on Wednesday and school continued unchanged until Thursday night.

“Student safety is always our number one concern, and we took every action to protect our students,” Wick said.

He said the threat was thoroughly investigated by police and school administrators.  and it was determined the threat was not credible. "At no time did we believe it to be true, due to the circumstances and the students involved," Wick said.

On Thursday, Master Sgt. Rakesh Dewan and Sr. Airman Jessica Woodall, of the 341st Security Forces Squadron at Malmstrom Air Force Base in Great Falls, arrived at the school about 7:45 p.m. Accompanying them was their trained German shepherd dog, Gina.

The junior high school was emptied of all staff and the search began shortly thereafter. No device was found.

Wick said school officials believe a student at the school wrote the threat on the wall in a girls’ restroom. He added that they have a suspect.

School officials notified students and parents ahead of time that they would search all bags and students and staff entering the school on Friday. Wick said Friday’s school day went smoothly.

He said a significant number of students did not show up for school on Friday, the last day of classes before spring break.