The parent who took the photo, Peter Gust, posted the image on his website, Wheel Memories, where it was visible until Nov. 12, when it was deleted. It can still be seen via the Wayback Machine, an internet archive.

A statement on Mr. Gust’s website said the page with the prom photos had been modified because of “malevolent behavior on the part of some in society.”

“To anyone that was hurt I sincerely apologize,” the statement said.

Not all of the students in the photograph were gesturing. Jordan Blue, a student wearing a red bow tie, could be seen standing in the upper right corner with his hands at his sides.

In a statement to Jules Suzdaltsev, a journalist, Mr. Blue said that the photographer had instructed the boys “to make the sign” and that Mr. Blue did not have time to leave because the picture “was taken within five seconds.”

He did not raise his arm because “I knew what my morals were and it was not to salute something I didn’t firmly believe in,” he said.

Brock Turkington, who also appeared in the photograph, told the television station WISC that it was not supposed to be a hateful gesture.

“As we were about to take that photo, the photographer instructed the boys to give a ‘high-sign,’” Mr. Turkington said in a statement to the station. “The photographer instructed us to extend our arms out, no one knew what a ‘high-sign’ was. I asked another student next to me ‘What are we doing?’ He responded, ‘Stick your arm out.’”