An eagle-eyed photographer captured the shocking moment an unhinged man — wielding a large knife — creeped up behind a group of unwitting musicians in Times Square on Wednesday morning.

Richard Moore, a Hell’s Kitchen-based photographer, said he first noticed the armed maniac standing on a granite block and yelling at around 10 a.m. on Broadway between West 43rd and 44th Street.

“I thought, ‘Oh this isn’t very good,'” Moore told The Post, saying he spotted the man occasionally flash a blade as tourists walked past.

As Moore got closer, he saw the unstable man jump off the block and start to trail a group of musicians.

“I noticed he had this knife in one hand and he got close enough to one of the musicians to put his other hand on the musician’s shoulder,” Moore said.

The shutterbug first thought the worst, saying to himself, “This isn’t gonna be good.”

But the knife-wielding man then suddenly backed off and went back to his block.

Moore said he still called 911, fearing the next encounter could unfold differently, and waited for about 12 minutes until cops arrived.

“Police got him from behind… I don’t know if they grabbed the knife or he dropped it,” he said.

“It was dealt with very peacefully and quickly,” Moore added. “They took him down safely for him and others.”

The NYPD did not immediately have any details on the incident.

It was unclear if the man was arrested or taken to the hospital for a possible psych evaluation.