'SNL' Star Chris Redd Attacker Used Brass Knuckles Which Blackened Both Eyes

The attacker who clocked 'SNL' alum Chris Redd in the face was wearing brass knuckles ... and there were two men involved in Wednesday's brazen New York City attack.

Sources connected to Chris tell TMZ ...  the attack left Chris with two black eyes and a huge gash on his nose, which required stitches. He was hospitalized after the attack and released shortly thereafter.

As TMZ reported ... both men were dressed as security guards and had masks covering their faces. We're told the attacker who approached Chris and hit him with brass knuckles was a heavyset man ... the other man was standing across the street, appearing to case the area.

Chris, we're told, was not able to identify anything about either suspect. Nevertheless, we're told he's meeting with cops who've gathered surveillance footage, with the hope of getting a lead -- if not from the images of the 2 men, possibly from their method of escape, be it on foot or in a vehicle.

Surveillance video could be key to cracking the case. Even if the 2 assailants ran for blocks, cops could piece together their movements with various surveillance cams.

You may recall ... in the Jussie Smollett case, cops used surveillance videos to track down the Osundairo brothers, who ran from the scene for blocks and then hopped in an Uber.

TMZ broke the story ... Chris had his Greg Yuna chain snatched off in the attack, but he was able to recover the bling, although it was in pieces. It can be easily restored.