UPDATE Friday, September 13, 2013 1:00 p.m.

A large number of students and their parents made the decision to stay home and not attend classes at Missoula's Big Sky High School, after it was revealed on Thursday morning that a bomb threat had been discovered on Monday in a school restroom.

Hatton Littman, Director of Technology and Communications at Missoula County Public Schools said Friday, September 13 was a slow day with normal classes, despite many students choosing not to attend.

"There are approximately 1,076 students this year at Big Sky High School," Littman said. "We've had a very slow day at school because a significant number of students chose to stay home with their families' consent. The important thing to remember is that it has been a normal instructional day here at Big Sky. The staff are phenomenal, and its been a really excellent day here on campus, I've been here several times today, and I continue to be impressed."

Littman responded to criticism by some parents and students that families were not notified about the bomb threat until Thursday morning, though it was discovered on Monday. The conclusion was not to shut down the school for four days just because some graffiti was discovered on a bathroom wall.

"We always do a thorough investigation to find out if there is any actionable information based on graffiti that was found," Littman said. "In concert with the Missoula Police Department it wasn't determined that that action was necessary."

Littman said the reaction from parents was mixed.

"Of course, there are parents that have heightened concern that want to ensure their student's safety," Littman said. "Some parents were upset and concerned that they weren't informed before 10:30 a,m. yesterday. Some parents felt that the district acted logically and responsibly, and informed them in time to make a decision for today. I have been incredibly proud watching the staff at Big Sky High School as they have been engaged and responsive with their school community. They've had a lot of conversations with a lot of parents and a lot of students."

Littman said police and school authorities are making progress in determining who was responsible for the graffiti. She said the words used were personal, and did not refer to racial or sexual issues, so no hate crime statutes were violated. The student or students responsible could face penalties ranging from suspension to expulsion, and could also face criminal charges.

Hatton Littman, Director of Technology and Communications at Missoula County Public Schools

Officials at Missoula's Big Sky High School sent out an 'Alert Now' message on Thursday, September 12, to all parents of students at the school, letting them know that on Monday morning, graffiti was found in a bathroom in the school that contained derogatory comments and a bomb threat.

Hatton Littman, Director of Technology and Communications at Missoula County Public Schools described the graffiti that was found earlier in the week.

"The graffiti had a lot of information in it that was really derogatory in nature, but there were two threats included," Littman said. "One was a threat to a student, and one was a threat to set off a bomb in the school on Friday, September 13."

Littman said an investigation has been underway all week at the school involving Missoula police and school authorities.

"There has been no indication of a threat to the students or the school based on that investigation" Littman said. "We were obligated to inform parents today that the threat was indicated to happen tomorrow, the 13th."

Littman said classes will go on as scheduled on Friday at Big Sky High School.

"There's no indication to the administration that based on any information they've found in the investigation, that they should cancel school tomorrow," Littman said. "However, we wanted to make sure we informed parents today that tomorrow was the date listed in the graffiti."

Hatton Littman, Director of Technology and Communications at Missoula County Public Schools:

Detective Sergeant Travis Welsh with the Missoula Police Department said an investigation is underway to determine a suspect in the threats made at the school.

"We are working to determine who is responsible for the threats right now, but we don't have a suspect," Welsh said. "We are continuing to interview students and staff members to try to track that down. We're also coordinating with officials on the best course of action to approach the next couple of days at the school. We are increasing our patrols around the school, and our resource officers are determining whether or not we need an increased law enforcement presence at the school."

Welsh said police are taking the threats made against the students in the graffiti and the bomb threat seriously.

"We are taking precautions, we are taking the potential of a bomb threat seriously," Welsh said. "We're trying to come up with ideas of how to approach the day."

Detective Sergeant Travis Welsh:

Parents of Big Sky High School students have been told they may keep their students home from classes on September 13, if they feel their safety might be threatened.