Cops were able to use surveillance video to track down the woman seen here brandishing a knife. She's 35-year-old Maricia Medrano. Cops went to her home Thursday night, executed a search warrant and found 2 airsoft guns ... similar to the one used by the perp in the first assault.

TMZ broke the story, the person who entered the store knocked down merch, left, and then came back wielding a knife, and that's when she was caught on surveillance video.

Medrano's been booked for assault and criminal threats. She's being held on $50,000 bail.

The video of her ranting with the knife is insane -- as is the fact news photogs didn't budge!