Two teenagers were killed in a shooting on Monday morning in North Carolina, the police said, and five other teenagers were hurt. They had gathered at a community park to witness or participate in a fight that the authorities said was “pre-planned.”

Hours after the first school bell typically rings, the teenagers made their way to Leinbach Park in Winston-Salem, N.C., a city of about 260,000 roughly 120 miles northwest of Raleigh.

Exactly how the fight unfolded is still being investigated, and no suspects were in custody, officials from the Winston-Salem Police Department told reporters at a news conference on Monday afternoon.

Chief William H. Penn Jr. suggested that social media had played a role in this fight and was changing the “behavior” of teenagers and younger children, generally, in fights. “I know I sound like the grumpy old man when I say that, but these fights now lead to weapons and shootings and videos,” Chief Penn said.

“This didn’t have to happen,” he added. “It’s senseless.”

Officers responded to 911 calls about a fight that had erupted in the park, about a five-minute walk from a middle school, just before 10 a.m. As the police drove to the scene, callers reported that shots had been fired.

Two boys, Erubey Romero Medina, 17, and Daniel Jimenez Millian, 16, were shot and pronounced dead at the scene. Mr. Medina was found in the parking lot and Mr. Millian inside the park.

Five other teenagers were shot, some with minor injuries and others in critical condition, the police said, without providing specifics. The police did not release their names. They included 14-, 15- and 17-year-old girls, a 19-year-old woman and an 18-year-old man.

Those injured may have been involved in the shooting, according to the police, who did not disclose the number or type of firearms used. The authorities did say the shooting was not gang-related.

Amanda Lehmert, a spokeswoman for the Winston-Salem/Forsyth County Schools, said that the district had experienced a “significant decrease in the incidents of reportable crimes” in recent years, and added that Mr. Millian was enrolled in a district school.

In a statement to WXII-TV of Winston-Salem, Mayor Allen Joines said, “I know this has caused fear, pain and heartbreak for many, especially our youth and the people who care about them.”

Don Phipps, the school district superintendent, said in an email that the police had quickly notified nearby schools, which enacted a security plan, but that there was no threat to students.