Sometimes, things are not as they first appear. That seems to be the case with an incident in Clarendon early this past Saturday morning.

Police say an officer patroling the bar district “observed a subject with a knife and detained him without incident” around 2:15 a.m. But soon, police say it became clear that the man with the knife was actually a would-be Good Samaritan and the victim of a crime.

“It was determined that two males were involved in a verbal altercation when the subject attempted to intervene,” the Arlington County Police Department said in a crime report. “Upon doing so, he was physically assaulted by one of the involved males and fell to the ground. He stood up, brandished a knife in an attempt to stop the assault, and walked away from the incident.”

“During the course of the investigation, the predominant aggressor in the assault was identified,” the crime report continues.

A 22-year-old man from Wareham, Massachusetts “was arrested and charged with Malicious Wounding and Drunk in Public,” ACPD said. “He was held on no bond.”

Also early Saturday morning, police responded to an armed robbery at a 7-Eleven store on Wilson Blvd in Rosslyn. More from the crime report:

ROBBERY (late), 2020-10310075, 1600 block of Wilson Boulevard. At approximately 5:00 a.m. on October 31, police were dispatched to the late report of an armed robbery. Upon arrival, it was determined that at 4:24 a.m., two suspects entered a business. Suspect 1 approached an employee and brandished a firearm while Suspect 2 demanded cash from the register. The suspects fled the scene on foot after stealing an undisclosed amount of cash. Suspect 1 is described as a White male wearing a black puffy jacket with a red shirt underneath, black ski mask and khaki pants. Suspect 2 is described as a White male wearing a black jacket, light blue ripped jeans and a black ski mask. The investigation is ongoing.