Four people were attacked — including an MTA worker and two teens — in separate incidents in the city subway system in just over 24 hours, cops said Tuesday.

A ski-mask-wearing maniac first punched a transit worker in the face around 5:40 p.m. Sunday on the northbound No. 7 train platform at the 74th Street and Roosevelt Avenue stop in Jackson Heights, Queens, police said.

The employee did not know his assailant, who snarled, “Do you know me?” before slugging the 46-year-old victim, authorities and law-enforcement sources said.

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The suspect ran off. and the victim was taken to the Elmhurst Hospital Center, where he was listed in stable condition, cops said.

The still-at-large menace had on a black ski mask at one point, clear glasses, a black jacket, black pants and black shoes, cops said.

The mayhem continued around 3 p.m. Monday, when an apparent stranger slashed a teen boy at another Queens subway station, cops said.

The 16-year-old victim was standing in the entrance to the Seneca Avenue M train station in Ridgewood when the brute knifed him in the back of the head, police said.

The victim was taken to Wyckoff Heights Medical Center, where he was listed in stable condition, authorities said.

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The attacker was still on the loose Tuesday.

Hours later, during the Monday evening rush, another teen was stabbed and slashed during a brawl in a Bronx subway station, police said.

The 18-year-old victim was fighting with a stranger, believed to be in his 30s, on the Freeman Street platform in Crotona Park East around 6:30 p.m. when the assailant stabbed him in the back and cut him on the neck and elbow, cops said.

The was taken to St. Barnabas Hospital, where he was listed in stable condition, and the attacker fled the scene. It wasn’t immediately clear what the pair was brawling about.

About a half-hour later, a menace also knifed a 33-year-old man across the forehead during a violent dust-up in the Rockaway Avenue No. 3 train station in Brownsville, Brooklyn, police said.

The victim was taken to Brookdale University Hospital Medical Center, where his injuries are considered non-life-threatening.

The attacker, a stranger believed to be in his 20s, fled the scene and has not been caught, cops said.

The string of attacks came hours after a brutish stranger randomly shoved a man onto Brooklyn subway tracks early Sunday, authorities said.

Without saying a word, the suspect pushed the 35-year-old victim onto the roadbed at 36th Street in Sunset Park around 4:55 a.m., cops and sources said.

That victim was helped back up onto the platform by responding cops, and he is listed in stable condition.