PORTLAND, Ore. (AP) — A man has been arraigned on assault charges for allegedly smashing a woman in the head with a basketball-sized boulder just after he was released from an emergency center for people experiencing mental health crises in Portland, Oregon.

Dwayne Simpson, of Missouri, on Wednesday was ordered held without bail until another hearing in Multnomah County Circuit Court later this week, The Oregonian/OregonLive reported.

Court documents say Simpson, 40, is accused of striking the woman in the back of the skull, causing her head to hit a concrete barrier as she fell to the ground.

Officers responding to the Unity Center for Behavioral Health in Northeast Portland on Tuesday saw a 55-year-old woman with “significant amounts of blood” around her, according to a probable cause affidavit.

Witnesses told police the woman appeared unconscious for about two minutes afterward, according to the affidavit written by Deputy District Attorney Michael Lee.

She was taken to a hospital for treatment. Her condition wasn’t released.

An officer recognized Simpson as having spurred a police response July 24 after 911 callers reported an agitated man screaming that he was “going to bash a woman’s skull,” according to the affidavit.

Police had Simpson taken to Legacy Emanuel Medical Center in that case, but he was released later that day, and more 911 calls were made about his behavior, documents said. Police were then unable to locate him, according to court documents.

Details about his recent treatment at the Unity Center weren’t released.

Simpson has been charged with first-degree attempted assault, second-degree assault and unlawful use of a weapon. It wasn’t immediately known if he has a lawyer to comment on his behalf.