A threat against Central High School in Grand Junction may be tied to a string of phoned-in threats nationwide, according to the Mesa County Sheriff.

In an update to the investigation - posted to the sheriff's office blog Wednesday - the MCSO says Tuesday's false threat to the high school is connected to "similar incidents across the country."

The call came in to the Grand Junction Regional dispatch center from a male subject, according to the sheriff's office.

The caller, claiming to be hiding inside the school with weapons, threatened the lives of students and staff at Central High School.

The prank call put the school on lockdown and prompted an evacuation of all 1,400 students and staff, room-by-room.

Similar threats were made against high schools in Kansas City, Missouri, Riverside, Calif. and Atlanta, Georgia.

Students at Oak Park High School in Kansas City were evacuated and police in Colorado say the threats there were made by the same person as Central High. They do not believe the threats were phoned in locally.

Investigators are now looking at the similar incidents for a possible connection and clues to the caller's identity.

After a search of campus, the threat was determined to be unsubstantiated.

"The Mesa County Sheriff’s Office, along with the Grand Junction Police Department, and the FBI determined that the threat is not real. We are confident there is not a credible threat to any of our local schools today or in the near future," the sheriff's office wrote.

The Mesa County Sheriff's Office is also investigating an anonymous phone call threatening Central High for Tuesday, made Monday night to local dispatch.

Deputies immediately followed up on the information and investigated it through the night. The threat was not substantiated.

The department still stationed additional deputies at the school Tuesday morning as a precaution.

School started as normal, but then the second threatening call came in at 9:54 am. While it is still early in the investigation, it appears the calls are connected, the MCSO says.

For details on Tuesday's incident, read the press release here.