TMZ Sports has obtained the 911 call made by the Postmates food delivery driver who says MLB player Bruce Maxwell pointed a gun at her ... and she's clearly shaken by the frightening ordeal.
The woman tells the 911 operator she was simply trying to deliver a food order to the Oakland A's catcher, but things got bizarre very quickly ... culminating with a shirtless Bruce sticking a gun in her face.
The woman says she wasn't sure if Bruce had done anything illegal because it was all on his property -- but the operator quickly assures her that pulling out a piece on a delivery person is wrong.
Cops responded to the scene and arrested Bruce for aggravated assault. According to the police report ... Maxwell cussed out officers and was uncooperative during the arrest.
Before this ordeal ... Bruce was known for being the only MLB player to take a knee during the National Anthem this season.
Now, Maxwell's also known for being banned from using Postmates again.