Additional security in 3 University Place schools after the threat posted on social media

The Pierce County Sheriff's Department is working with the School District of University Place and investigating after a post on social networks threatened violence in three schools.

Officials said the publication was found on Instagram and threatened violence at Narrows View, Drum and Curtis schools.

The schools will be open on Friday.

Detectives are working to determine the source and credibility. As of Thursday night, investigators did not find information indicating that the threat is credible.

The additional security will be at the affected schools on Friday morning.