PEWAUKEE, Wis. (AP) — A Milwaukee area school district has canceled classes after receiving a security threat.

Pewaukee district schools will be closed Wednesday. Superintendent Mike Cady says administrators are working with local police who are investigating the unspecified threat which was received Tuesday night.

The threat comes just before the National School Walkout planned for Wednesday. Students across the country are planning to walk out of classes to protest gun violence and call for gun control in the wake of the Feb. 14 shooting that killed 17 people at Marjory Stoneman Douglas High School in Parkland, Florida.