SPOKANE VALLEY, Wash. — UPDATE: Spokane County Sheriff's officials said Wednesday night that one juvenile has been arrested in connection to a threat investigation at Mead High School.

Officials said School Resource Deputy Jeff Rogers contacted and arrested a 13-year-old girl in connection to the threat.

The girl has been booked into the Spokane County Juvenile Detention Facility for threats to bomb or injure property.

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UPDATE: The Spokane County Sheriff's office said it has identified the suspects involved in making social media threats against three local schools.

Several juveniles were involved. The East Valley High School and West Valley High School threats were connected.

The Mead High School threat was not connected. No arrests have been made.

The investigations will be forwarded to the Spokane County Prosecutor's Office. Felony charges are expected.

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Spokane Valley and Spokane County deputies are continuing to investigate a social media threat made against East Valley Monday night on social media.

Meanwhile, the East Valley School District has decided to remain open on Wednesday and keep the school on "lockout." This means that all exterior doors will be locked throughout the day, but school activities will go as normal inside the building. all high school students will remain on campus and there will be no outdoor activities for elementary.

On its website, the district said the threat was made on Snapchat, but believed to be from a fake account.

The superintendent said 82 percent of students stayed home Tuesday. Normally, around 10 percent miss school on any given day.

In a press release Tuesday afternoon, the Spokane County Sheriff's Office said additional posts have been reported referencing West Valley High School and Mead High School. Officials said the districts have been made aware of the information and are working with school resource officers to ensure the safety of students and staff.

Authorities believe the accounts used are fake but detectives are working to identify the person(s) responsible.

Anyone with information regarding this investigation or can help identify the suspect(s) is urged to call Crime Check at 509-456-2233, contact a School Resource Deputy or School Official immediately.

Law enforcement was present on campuses throughout the day.

The Spokane County Sheriff's Office in a release Tuesday morning emphasized the importance of "see it, say it".

"Unfortunately, these threats continue to happen at schools here and across the Nation. We ask parents to talk to their school aged children about the use of social media and the consequences of their actions. We also ask if a threat is observed on social media that it is reported immediately, not merely forwarded or spread around the internet," the Sheriff's office said.

The full message from the East Valley Schools superintendent reads:

My hope is that you already know this, but just in case, I will summarize our current situation. At about 9:45 pm last night I was informed of a threat made via snapchat. The message read "Watch out if you go to EV. Some of you are going to die tomorrow" (with a gun emoji).

We do not know who created this. We believe it was sent through a fake account. At the time, only high school students were sent the message. I'm not sure of how snapchat works, but others outside of the high school could have received this through people resending, but all of the information I received came last night from high school students. So it is our belief that the high school was the target.

The Sheriff's Department is sending additional resources to our district today. Not sure how many extra people we will get, but we will put them first at the high school, then at the middle school, and then at our other schools. Most likely the elementary will have patrol cars driving around the schools. We will have a law enforcement presence this morning.

I completely understand the fear and anxiety this creates for all of us. We are doing everything we can think of to find the source of this threat and to ensure everyone's safety. In the meantime, we cannot let our fear get in our way of doing what we need to do.

If anything new comes to my attention, I will let you know as soon as I can.

Original message:

Dear Parents, Guardians, Staff and Students,

At approximately 9:45 pm I was notified of a Snapchat post threatening violence at school tomorrow. The message reads, "Watch out if go to EV. Some of you are going to die tomorrow." (includes a gun emoji).

Currently, our deputy resource officer and administrative team are investigating the matter to determine the credibility of the message and identify who sent it. Please talk with your children to see if they know anything and please send me any information you may have (sheak@evsd.org).

At this point, we will have school tomorrow. We are in the process of asking for additional law enforcement presence in our schools. These events create fear and anxiety for all of us. If you choose to keep your children home, I completely understand, and his or her absence will be excused.

As we work on this issue during the night, a decision to cancel school may be determined so please watch the news as well as your email and text messages tomorrow morning for any announcements.

There are lots of questions and I apologize for not having the answers, but we are determined to get to the bottom of this and ensure the safety and security of our students and staff.

Kelly Shea, Superintendent