SOUTH PASADENA (CBSLA.com)  —  A massive effort is underway to find a missing 5-year-old South Pasadena boy.

CBS2’s Jeff Nguyen said officials are particularly concerned about the boy’s welfare given the circumstances of his disappearance.

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The boy’s 35-year-old father was allegedly found passed out near his car in Arroyo Seco Park Saturday morning. It remains unclear why the dad was passed out.

The boy is identified as  Aramazd Andressian.

He’s described as just under four feet tall — about 55 pounds – with brown hair and brown eyes.  He also has a small mole on one shoulder.

Police say his parents are going through a divorce and his father was supposed to hand the boy back to his mom this morning.

At a news conference Saturday evening, Art Miller, the chief of South Pasadena Police, said the father was questioned at length — “for several hours” — and was ultimately booked on two counts — one for child abduction and another on child endangerment.

Police said the father had “little recollection” of what happened to the boy and exactly when he got separated from the child or where he may have taken him. Ultimately, police described the father as “not very forthcoming.”

Authorities speculated that someone who knows the family may have taken the boy to make sure he is/was safe.

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Earlier – a police dog was brought in to help with the search.

When paramedics arrived at the park — they didn’t know that a child was missing.

They only treated the father and transported him to the hospital. The father was later released from the hospital and then questioned by investigators.

At this point  police don’t know what happened to the boy. At a press conference Saturday afternoon, they said the search for Aramazd was continuing. They said the very same thing Saturday evening.

Officials are focusing on the park because that is where his father was found.

“I will say this, anytime a child is missing regardless of their age whether a juvenile – law enforcement pulls out all of the stops. That’s why we have this multi-agency response here today,” said Chief Miller.

For now – police don’t believe the boy’s father harmed  the child.

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The boy’s mother reported him missing — when the father didn’t bring him to her home.