DIXFIELD — Schools in Regional School Unit 56 will extend their closure after a second COVID-19 case was discovered Tuesday, Superintendent Pam Doyen wrote in a notice to students, staff members and families.

RSU 56 officials decided Monday to close for three days for cleaning because of one case of COVID-19.

They have now extended the closure to 14 days, and plan to reopen schools Sept. 29.

The state requires schools be cleaned after confirmed cases of the coronavirus.

RSU 56 students started classes last week at Dirigo High School in Dixfield and at T.W. Kelly Dirigo Middle School and Dirigo Elementary School, both in Peru.

“There is a possibility that other staff or students came in contact with these individuals and, therefore, may be exposed to the virus,” Doyen wrote in her notice. “Again, out of an abundance of caution, the RSU 56 schools will be closed to students for 14 days.”

On Monday, the Region 9 School of Applied Technology in Mexico reported two students had been diagnosed with COVID-19. The school takes students from School Administrative District 44’s Telstar High School in Bethel, RSU 10’s Mountain Valley High School in Rumford and RSU 56’s Dirigo High School.

The technical school also chose to close for 72 hours for cleaning.

An RSU 10 student with a confirmed case of COVID-19 had only attended Region 9 and not Mountain Valley High School, RSU 10 Superintendent Deb Alden wrote in a notice Monday. For that reason, RSU 10 schools — with students from Rumford, Mexico, Buckfield, Hanover, Hartford, Mexico and Sumner — were not closing.

“I’m glad that RSU 56 had their framework (for COVID-19 back-to-school instruction) approved, and that the CDC (Maine Center for Disease Control & Prevention) has provided a solid outline of how to proceed and they have been great working with us and helping us get through this,” Doyen said in a telephone interview Tuesday.

Those from RSU 56 who have questions should call Doyen at 207-562-4251.

In Region 9, call 207-364-3764.

In RSU 10, call the Central Office at 207-369-5560.

In SAD 44, call the high school office at 207-824-2136.