The man was contacted at about 5:20 a.m. near Shattuck Avenue and Allston Way, sheriff's spokesman Sgt. Ray Kelly said.
The man was unable to talk because of a severe disability and had no identification on him. He also had an injury to his right arm.
The man had a BART ticket on him that originated in Richmond on Monday morning and showed that he left the BART system at the West Oakland station at about 10:10 a.m. the same day.
Bay City News contributed to this report.