A canine-unit police officer responded to Union Square on Halloween night after four male teenagers were shot and one man was stabbed at 12:47 a.m. on Nov. 1. The incident started in a dispute in a McDonald’s and spilled into the park, police said. At the same time, a large Halloween gathering in the park was breaking up, witnesses said. The four teens were taken to St. Vincent’s Hospital and the man was removed to Bellevue Hospital. All were in stable condition. It was not known how many individuals were involved in the shooting. There were no arrests.