LOMA LINDA (CBSLA.com)   — The family of a missing 71-year-old man is concerned for his well-being.

Nam Chung Woo was last seen by family members at his residence in Loma Linda, on May 10, 2014 at approximately 10:30 a.m.

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Family members discovered him missing about two hours later and began searching for him.

Woo’s family members searched the surrounding streets and neighborhood for more than four hours.

The family called San Bernardino County  Sheriff’s Deputies for assistance. An extensive ground search and aerial search have been conducted.

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Woo is considered a critical missing person.

The missing man has Alzheimer’s disease and requires medications. He also uses medications for anger management. He has not taken his medications today and the family says he may appear to be acting strangely.

If members of the public see Woo they are urged to contact the Sheriff’s dispatch at (909) 387-8313 or 911 immediately.

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Woo is 5 feet, 6 inches tall and about 140 pounds. He has gray hair and brown eyes.