More written threats surfaced Friday morning in bathrooms at Dimond and Bartlett high schools in Anchorage.
The graffiti discovered at the two schools joins threatening messages found at Dimond last week as well as a threat and a "hateful slur" discovered Thursday at Service High School. The messages prompted bathroom and hall access restrictions, student searches and additional law enforcement presence.
No arrests have been made, but school officials are asking for the public's help.
"We are spending extreme time and energy focusing on the threats of violence and we need our students and families to continue to share any information that you may have," school district spokeswoman Catherine Esary said in an email statement Friday. "We want the Anchorage Police Department to have information and be able to solve these crimes."
Dimond principal Tina Johnson-Harris found the latest message just after 9:30 a.m. Friday, according to the school district. The substance of the threat wasn't immediately clear.
Within two minutes, school officials saw a social media post about the threat from someone describing themselves as a Dimond parent, Esary said.
Asked if social media posts are not helping the situation, she answered by email: "We are asking that parents also share what they or their children know with their child's school or the district."
Dimond families received official text and email messages by 11 a.m., according to the district.
"Backpacks have been searched each day this week and we are continuing to investigation this situation," Johnson-Harris wrote in a message to families. "While bathrooms have been secured, Dimond is not in a stay put or a lock down."
At Bartlett, meanwhile, a student reported a threat similar to the others on a wall in a bathroom Friday morning.
"Security and administration immediately began reviewing camera footage, sent communication to staff and ensured students were safe," principal Sean Prince said in a message to parents and families. "At this time, we have determined that the school and its students, staff and faculty are safe."
All three schools are working with police, authorities say.
School resource officers are leading the investigation in cooperation with the district, APD spokeswoman Kendra Doshier said in an email.
"We are working together to ensure that those responsible are held accountable," Doshier wrote. "We understand the anxiety surrounding these incidents and our top priority will always be ensuring the safety of our community."