(The Center Square) – Highline Public Schools is canceling school two days in a row after detecting a potential cyber attack, marking the third to a public entity in King County this year and the second in the last 15 days.

The school district announced n a social media post on Sunday that all of its schools will close along with all activities and athletics.

“We have detected unauthorized activity on our technology systems and have taken immediate action to isolate critical systems. We are working closely with third-party, state and federal partners to safely restore our systems,” the district stated in the social media post.

Monday was set to be the first day of school for kindergarten students.

“We recognized the burden this decision places on both families and staff, but student safety is our top priority, and we cannot have school without these critical systems in place,” the district added.

On Monday, Highline Public Schools announced school would continue to be closed on Tuesday as investigation into unauthorized activity on the district’s technology systems is ongoing.

The district’s critical systems are still offline.

Highline Public Schools serves approximately 17,800 students within the City of Burien, and parts of Sea-Tac, Des Moines, and unincorporated King County.

Highline Public Schools said it has not seen evidence of staff, student, or family information being compromised as a result of this cyber attack.

The cyber attack on Highline Public Schools is another in a series of such attacks on King County public entities.

Nearby, another public entity was victim to a cyber attack that is still in the process of recovering. On Aug. 24, the Port of Seattle announced it was experiencing an internet and web systems outage, which impacted some systems at the airport. ​​Soon after, Seattle-Tacoma International Airport, better known as SeaTac, requested travelers to avoid checking their luggage after acknowledging it was hit by a cyber attack.

The Port of Seattle website is still down as part of the system outages, but Wi-Fi is back up and flight and bag information displays are operating for all airlines, except United, as of Monday.

In late May, the Seattle Public Library was hit by a cyber attack that impacted its website, Wi-Fi, online catalog and loaning system. It took several months for services to return for users of the library.