ANTIOCH -- Police arrested a teenage boy on felony assault and robbery charges Thursday in connection with a May 18 robbery and attack that critically injured an 83-year-old man near an Orchard Supply Hardware store, authorities said.

The 15-year-old, whose name is not being released, was booked into the Martinez Juvenile Detention Facility after police gathered enough evidence to detain and interview him about his alleged involvement in the robbery and brutal beating, Antioch Police Sgt. Tony Morefield said.

The 83-year-old victim, who remains in the hospital in critical condition, was unconscious and bleeding when police arrived at 4873 Lone Tree Way in response to a robbery in progress, Cpl. Mike Hulsey said.

Authorities have not revealed what was taken during the robbery, but said that the man suffered serious head trauma during the incident. Police investigators said the man was beaten and assault charges are consistent with that. The head injuries were not the result of a shooting, police said.

No further information was immediately available about the teenager or his suspected involvement in the attack, though the Contra Costa County District Attorney is set to review the case in the coming weeks, Morefield said. The investigation is ongoing.

Contact Erin Ivie at eivie@bayareanewsgroup.com. Follow her at Twitter.com/erin_ivie.