UPDATE, 3 p.m. Tuesday: Robert and Constance Thomas have been located safe and sound, according to the Mason County Sheriff's Office. The Silver Alert has been canceled.
ORIGINAL STORY: The Washington State Patrol has issued a Silver Alert for an 87-year-old man and 88-year-old woman from Shelton, who are believed to have left a residence in Thurston County on Monday night, and did not return to their home.
Robert and Constance Thomas left the residence in Olympia at about 8:30 p.m., driving a 2007 silver Ford Freestar van, with Washington license plate No. 90441DP.
Both are believed to have dementia and other medical problems, and were last seen near Interstate 5 in the Portland area at about 10:30 a.m. Tuesday, asking for directions to Washington, according to the Mason County Sheriff's Office.
An earlier tweet from the Sheriff's Office on Tuesday afternoon suggested they may have been traveling to California.
A debit card belonging to one of them was last used at a gas station in Brooks, Oregon at about 3:30 a.m. Tuesday.
Robert Thomas is listed as a 5-foot-11, 200-pound white male with gray hair and blue eyes.
Constance Thomas is a 5-5, 175-pound white female with silver hair and blue eyes.
Anyone with information about their whereabouts is asked to call 911.