Certain private schools; certain memoranda of understanding with local law enforcement permitted. Permits the administration of any private elementary or secondary school in the Commonwealth that has a campus that is (i) located wholly within one locality but (ii) contiguous to another locality to enter into a memorandum of understanding with the local law-enforcement agency in such contiguous locality governing such agency's response to any law-enforcement emergency involving any immediate threat to life or public safety on such campus in accordance with the authority granted to the local law-enforcement agency pursuant to relevant law to so respond.