Portland police are looking for a 18-year-old man they believe is suffering from a "critical mental health situation" and are asking for the public's help.

Henry Willard Smith III was last seen about 6 p.m. near the Marriott Hotel

, said Sgt. Pete Simpson, a spokesman for the

. He hasn't been seen or heard from since.

Smith is 5-foot-11, 150 pounds and has medium-length brown hair and blue eyes. He might be driving a gold 1986 Jaguar XJS with Oregon license plate 9P1363.

Investigators said they believe Smith is at an "immediate risk" and ask anyone who knows where he is to call 9-1-1. Anyone with additional information is asked to call Detective Mike Weinstein at 503-823-0446.

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