A Seattle-area school system serving more than 17,000 students is closed Tuesday for a second day to start the school year after a cyberattack caused network outages. 

Highline Public Schools, headquartered in Burien, Washington, released a new notice on Monday afternoon confirming that that facilities would remain closed after all activities, sports and meetings were canceled on Monday as well. 

“Our investigation into unauthorized activity on our technology systems is ongoing, and critical systems are still offline,” the school said. “We understand canceling school is a significant disruption for our families and staff, but student safety remains our top priority.” 

The school district — which runs 35 schools with about 2,700 staff members — did not respond to requests for comment about whether they are dealing with a ransomware attack. No group has come forward to claim the incident. 

On Monday, officials said they isolated critical systems after discovering “unauthorized activity,” calling in assistance from federal and state law enforcement agencies as well as cybersecurity experts. 

The shutdown hindered the first day of kindergarten for many families in the community but the school district said it could not “have school without these critical systems in place.”

School and central office administrators are still expected to report to work despite the shutdown.

The Seattle region has had multiple ransomware attacks on key institutions in the last six months. 

Just one week ago, the Seattle Public Library said it had finally restored nearly all of the public services impacted by a ransomware attack that took place on Memorial Day. 

It has taken the library system weeks to resume access to public computers and other offerings. Later this month the library will restore the final system left: access to microfilm/microfiche. 

Ahead of the Labor Day holiday two weeks ago, Seattle’s airport and seaport were knocked offline — forcing airlines to process baggage claims with pen and paper. White boards replaced screens that showed airplane gate numbers. Systems only got back up and running this weekend. 

No hacking group ever took credit for either attack. The NoEscape ransomware gang previously attacked the Seattle Housing Authority last October. A prominent cancer center based in Seattle was also hit with ransomware in December.