West Point military academy has held an annual pillow fight every year at the end of the summer to cap an intense session of grueling training for first-year cadets. The fight, meant to build class spirit and give cadets a way to relax, caused several serious injuries after students put hard objects in their pillowcases, the New York Times reported Friday.

At least 30 cadets were injured, including 24 with concussions despite the requirement that all cadets wear helmets, West Point confirmed Thursday. Other injuries included broken ribs and legs and several dislocated shoulders. A video of the fight, which took place Aug. 20, was posted to YouTube and in it viewers can see that more than one cadet appeared to have a blunt object in his or her pillow case.

Several people were knocked unconscious and immediately returned to the fight when they awoke. "If you don't come back with a bloody nose, you didn't try hard enough," one cadet told the New York Times.

A traditional snowball fight at the U.S. Air Force Academy in Colorado Springs, Colorado, turned into a similar brawl in 2012. A spokesperson for the academy reported 27 injuries including concussions, cuts and even a human bite.

Upperclassmen organized and oversaw the West Point event, and leaders at the school said they were proud of the team-building despite the injuries. “[The upperclassmen] allowed the spirit activity to occur out of the desire to enhance the spirit of the class,” said Col. Christopher Kasker, a spokesperson for the academy.

The pillow fight has been a West Point tradition since 1897, and no talks of canceling the event or disciplining those involved have surfaced.

“West Point applauds the cadets’ desire to build esprit and regrets the injuries to our cadets,” Kasker said, according to the Times, adding “We are conducting appropriate investigations into the causes of the injuries.”