A convicted sex offender is accused of brutally raping a Spokane Valley Zip Trip employee inside the convenience store early Saturday morning.

Michael D. Rush, 36, was arrested on suspicion of first-degree rape and second-degree assault after Spokane County Sheriff’s deputies responded to the store’s alarm system around 5 a.m.

When deputies arrived, they found a partially dressed female clerk in the bathroom. The clerk told authorities she’d been beaten, strangled and sexually assaulted by Rush, according to the Sheriff’s Office.

Rush was exiting the bathroom when deputies arrived, the Sheriff’s Office said, and was immediately detained. The store, which is open 24 hours, was dark inside when deputies arrived, they said, but the door was unlocked.

Rush is a convicted felon and Level 3 sex offender out of Chelan County.

The victim was transported to a local hospital for serious but not life-threatening injuries.