A 14-year-old Colorado Springs boy was arrested on suspicion of 11 counts of first-degree murder and attempted murder in connection with a shooting at a pop-up party in Aurora on Sunday.

The boy, whose name is being withheld due to his status as a minor, faces one count of first-degree murder, 10 counts of attempted murder and two counts of possession of a handgun by a juvenile, said Mark Hildebrand, chief of the Aurora Police Department’s investigations division, at a news conference Thursday afternoon.

Police have identified three women — two 15-year-olds and one 20-year-old — who were injured when the boy shot into the party crowd after a fight broke out around midnight Saturday, Hildebrand said. One of the victims, 15-year-old K’Tahna Jordin Smith, died shortly after arriving at the hospital that night.

“We send our condolences to the family of the young female who lost her life senselessly,” Hildebrand said. “This is a tragedy.”

Police initially responded to the scene at about 12:30 a.m. Sunday morning near an Aurora fire station in the 12000 block of East Hoffman Boulevard, according to a news release received on Thursday from the Aurora Police Department.

15-year-old identified in fatal Aurora shooting

The shooting had broken out after a pop-up party involving juvenile individuals, many of them female, had led to a fight, Hildebrand said. Many of the people at the party were drinking alcohol and livestreaming the event on social media, resulting in others in the area joining in.

Currently, police believe that the fight involved two distinct groups of people: the group that initially began the party in Denver before relocating it to Aurora and another who came from Colorado Springs, the group that included the shooter, Hildebrand said. Police currently believe there were members from different gangs at the event, but do not think that the violence was one gang against another.

Additionally, police believe that the group from Colorado Springs was the initiator of the violence that broke out, Hildebrand added. The shooter, who police said was part of that group though they do not yet know exactly why, fired into the crowd of people.

“The community as a whole needs to do a better job of controlling the actions of our juvenile population, ensuring that they are safe and that they’re not engaging in this type of behavior,” Hildebrand said.

A cell phone video obtained and redacted by Aurora police depicts what appears to show a group of at least several people beating an individual on the ground. Police currently believe that immediately after the fight is when the shooting occurred, Hildebrand said.

“We have a juvenile population that is going out well after hours, they’re posting on social media platforms encouraging multiple people to come to these locations, we even have information that they’re participating in girl fight clubs,” Hildebrand said. “The behavior that we’re observing is completely unacceptable.”

The 14-year-old shooter was arrested on an unrelated warrant for motor vehicle theft by the Colorado Springs Police Department, Hildebrand said. Upon searching his residence, police found two handguns, a 9mm and a .380-caliber.

Police currently do not know if the guns found in his residence were the ones used in the shooting, but multiple types of bullet casings were recovered at the scene, Hildebrand said.

“A 15-year-old female lost her life during this, in this senseless act,” Hildebrand said. “A 14-year-old armed himself with two firearms … and made the conscious decision to use them against a group of people.”