The dispute happened just after 6:30 p.m. inside the W. 14th St. store.
According to police, the suspect was told by the security guard that he had to wear a mask if he was going to enter the store.
The man refused, the two exchanged words, and then the suspect pulled out a sharp object.
He stabbed the 37-year-old security guard in the back, forehead, and left arm.
Police say the suspect took out some sort of cutting instrument and stabbed the security guard in the body.
He was taken to Bellevue Hospital where he is expected to survive.
"I saw him when they took him out on a stretcher, two paramedics followed by about five or six policemen, but I did see cops running in and running to the back," witness Roberto Monticello said.
The suspect fled from the scene and it's believed he run into the 14th St. subway station.
He is described as a male, Black, 5'6, in his 20's, last seen wearing a black mask, black sweatshirt, and blue jeans.
Police continue to search for him.
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