Eleven high school lacrosse players in Syracuse, N.Y., turned themselves in to the authorities on Wednesday in a hazing incident involving younger teammates that the district attorney said included a gun and a knife.

William J. Fitzpatrick, the district attorney for Onondaga County, had given the players 48 hours to surrender and turn in the gun or face criminal kidnapping charges.

He called the episode “hazing on steroids,” and said the students would be charged with unlawful imprisonment, a misdemeanor.

“I cannot adequately express to this community the level of stupidity and lack of judgment involved in this case,” Mr. Fitzpatrick said at a news conference on Tuesday. “This goes way, way beyond hazing.”

Mr. Fitzpatrick said a group of older players from the Westhill High School boys’ varsity lacrosse team took several younger players to a remote area last Thursday after a dinner at a fast-food restaurant. A driver pretended to be lost, and another group of students emerged from the woods dressed in dark clothing and brandishing at least one handgun and one knife, he said. Mr. Fitzpatrick said one victim’s head was covered, and he was tied up, bundled into the trunk of the car and taken to another remote location.

He was left there for an unspecified period of time and then eventually driven home. Other victims escaped, Mr. Fitzpatrick said.

Video was recovered that showed some of the older players finding the episode “amusing,” according to Mr. Fitzpatrick.

“I’ve seen the videotape of what happened to this young man,” he said. “It is not a rite of passage. It is not a trivial matter.”

The names and ages of the players who turned themselves in were not released. Mr. Fitzpatrick said some of them are thought to be at least 18.

The players were issued appearance tickets in family court or criminal court, depending on their ages, and were released to the custody of their parents.

On Tuesday, Mr. Fitzpatrick publicly offered them two days to turn themselves in and be charged with unlawful imprisonment and released without bail.

The hazing was first reported to the police by a school resource officer, and the sheriff’s department spent four days investigating before Mr. Fitzpatrick spoke publicly.

Westhill High School canceled the remaining nine games of the lacrosse team’s season because of the incident. Steve Dunham, the Westhill Central School District superintendent, said in a statement that a majority of the players on the team were not involved and had not been aware that the hazing was being planned. He acknowledged that canceling the season could amount to a punishment for those players, but said a larger issue was at play.

“We must address the culture of the program, and the most appropriate way to do that is with a reset,” he said in the statement.

Hazing is prohibited in the Westhill school district. Lisa O’Reilly, the president of its board of education, said in an email that the district was working with law enforcement.