Ken Long got onto the bus at Sutter Street and Van Ness Avenue this morning and has not been seen since, according to police spokesman Steve Mannina.
Long is considered at risk because he has the approximate IQ of a 7-year-old and only speaks Mandarin, Mannina said. He is also on medication for diabetes and is not carrying identification.
Long is 5 feet 5 inches tall, weighs 160 pounds and has brown eyes and black hair. To view a photo of Long, go to http://www.sfgov.org/police. Anyone with information about Long's whereabouts is asked to call the police department tip line at (415) 575-4444.