Cops say Zac Stacy is on the run following the brutal attack on his ex ... claiming the former NFL running back has fled the state of Florida in attempt to avoid arrest.
The Oakland Police Department tells TMZ Sports ... officers responded to the domestic violence call "within two minutes" last Saturday -- but claim Stacy had already left the scene when they arrived.
Per a OPD spokesperson, cops immediately launched a manhunt for Stacy -- but say they have yet to locate the ex-St. Louis Rams running back.