2:23 PM PT -- The Oakland Police Dept. says it has seen video of Anthony Rendon's altercation with the fan ... and it has now launched an investigation into the matter.
"Although we are still unaware who the victim is," an OPD spokesperson said in a statement to TMZ Sports on Friday afternoon, "surveillance video of the incident has surfaced. As a result, OPD created an incident, made a report, and is actively investigating."
Angels star Anthony Rendon -- a former World Series champion -- was involved in a heated confrontation with an A's supporter following L.