ALBUQUERQUE, New Mexico (CBS SF) – Authorities in New Mexico believe a 5-year-old boy who has been missing for nearly a week may be with his mother in the Bay Area.

According to the Bernalillo County Sheriff’s Office, 5-year-old Mario Hernandez went missing on May 6 in the community of South Valley, near Albuquerque. Mario was last seen with her mother Nancy Flores, who does not have custody.

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Deputies said Flores refuses to return Mario and has a felony arrest warrant for custodial interference.  The sheriff’s office has issued an Endangered Missing Juvenile Alert in the case.

Mario Hernandez, Nancy Flores (Bernalillo County Sheriff’s Office)

“We are concerned for Mario’s safety,” deputies said in a tweet Wednesday.

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Flores works as a house cleaner in the Bay Area and deputies suspect they may be in San Francisco.

Mario was last seen wearing a red spider shirt, gray shorts with red stripes, along with black shoes. He is described as standing 3-foot-6 inches tall, weighing 50 pounds, with brown hair and brown eyes.

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Anyone with information about the case is asked to contact the Bernalillo County Sheriff’s Office at 505-798-7000 or to call local law enforcement.