A guy who wanted to chow down at an IHOP without a face covering wouldn't take "no mask, no service" for an answer -- because cops say he went to town on the staff with a knife.
Law enforcement sources tell TMZ ... this wild incident went down Tuesday in Queens where surveillance video captured the horrifying scene. At first, you see the customer in the waiting area with another guy -- although, we're told there were at least 3 men who rolled in together.
Looks like a staffer's telling him to mask up, which seems to piss him off. He gets up to argue, and appears to leave the building -- but when the whole crew comes back, he's way more agitated.
The video shows the guy who allegedly refused to put on a mask storm back into the IHOP and charge past a table and other waiting customers ... apparently trying to get at someone off-camera.
While trying to get a hold of that person, the guy reaches over and grabs something from his friend -- cops say it was a knife -- and then chases some workers through the restaurant. Toward the end of the video, he actually swings at someone before booking it.
According to our sources, the man swung at a 40-year-old female employee and cut her arm, which required stitches.
As for the guy here ... we're told he and his pals made a clean getaway, but cops are on the hunt.