Cops tell TMZ they were called at around 5:45 PM, but the man brandishing the weapon -- meaning he wasn't pointing at anyone -- was no longer there. When cops returned later, they found the man and a brandishing report was filled out.
We're told it's under further investigation.
UPDATE: OctoMom's neighbors told us the man in question was simply bringing the unloaded gun inside his house from his car. They also said everyone is sick of OctoMom's media attention, saying their kids can't play in the cul-de-sac anymore. These problems shouldn't last much longer ... because OctoMom's house is about to hit the auction block.