An Arizona school district has canceled all classes on Tuesday after multiple threats were reported.

In a letter posted on its Facebook page and sent to school families, the Sahuarita Unified School Distrrict south of Tucson said all schools, including its Early Childhood Center and L.I.N.K. program, would be closed Tuesday.

In addition, all after-school activities for grades K-8 are canceled. High school activities will be evaluated on a case-by-case basis, the statement said.

According to district officials, a threat was posted against Sahuarita Middle School on Monday around 4:30 p.m.

That came after a previous threat was made against three district schools within the previous 24 hours, the statement said.

"These incidents are quite stressful for schools, staff, students and parents, but we must take every threat seriously,'' the statement said. "We will continue to work with the Sahuarita Police Department in support of a timely resolution to this matter.''

The statement reminded parents and students that anyone who makes a threat against a school can be subject to arrest and school discipline.

Anyone with information about any of the incidents is asked to call Sahuarita Police at 520-344-7847, or 88CRIME. A report also can be submitted by calling 911.