A homeless man went on a stabbing rampage in the heart of Greenwich Village on Monday night, threatening a teen with a pair of scissors and then stabbing two people with the tool, critically injuring both of them, police said.

Douglas Gaston, 50, attacked the duo in front of a Salvation Army headquarters on West 14th Street near Sixth Avenue around 9 p.m.

He allegedly plunged the scissors into the chest of a 42-year-old Bronx resident before jamming the blades into the armpit of another 32-year-old homeless man, police said.

The pair were taken to a nearby hospital in critical condition, police said.

It’s not clear why Gaston attacked the men, but police said they may have exchanged words just before the incident.

Shortly before the stabbing, Gaston allegedly menaced a 15-year-old boy with the scissors, but the teen managed to get away from him unharmed.

Gaston has been charged with two counts of assault, reckless endangerment, possession of a weapon and menacing, police said.

Police said he has nine prior arrests but declined to share details of those incidents.