Police say the shooting happened around 6:30 p.m. near West 71st Street and Amsterdam Avenue.
A witness named Hugo Souza, who was just steps from the shooting, told Eyewitness News that there were about five or six people running toward the nearby McDonald's after shots rang out.
He says one of the people who ran inside was a 17-year-old boy who was shot once in the right leg.
Witnesses say friends of the victim took off their shirts to make a tourniquet for his wounded leg.
"They were panicking," said witness Melanie Mate. "Some of the guys were calling somebody that their friend got shot. Some were calling 911. And in a few minutes the police came."
The police and curious trick-or-treaters converged on the McDonald's on what was supposed to be a warm night of fun.
As families, and kids in costumes, packed the streets, some were not sure if the Halloween night crime scene was real.
Police covered shell casings with cones around the corner, where witnesses had seen one young man running in the opposite direction from the victim and his friends.
"Ran out to the front of the house and I saw the guy running," said Upper West Side resident James Eliopoulos.
He says he heard about four or five gunshots.
The 17-year-old was taken to NewYork-Presbyterian/Weill Cornell Medical Center where he's expected to survive.
Police say a 19-year-old man was also shot in the shoulder and arm, and later showed up at Mount Sinai Hospital where he's in stable condition.
Authorities say they are looking for two male suspects in their 20s who fled the scene on a Citi Bike.
The first male was wearing a navy blue sweatshirt, black pants and a grey backpack. The second male was wearing a black-hooded shirt and blue jeans.
There's no word yet on what led up to the shooting, and no arrests have been made.
The investigation is ongoing.
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