Don't panic if you see a lot of flashing lights at Spokane Valley Mall late Saturday and early Sunday -- multiple law enforcement and fire agencies are staging an "active shooter exercise" there.

Spokane County Sheriffs, Spokane Police, Spokane Valley Police, Spokane Valley Fire, local hospitals, the local ambulance service provider, the FBI and the Washington State Patrol all will be involved, the sheriff's office said in a news release.

The full-scale exercise will help those agencies evaluate their response plans. Staging will begin at 11 p.m.; the exercise will begin at 2 a.m.

It's not open for public viewing, the sheriff's office notes.