Several revelers in Chicago, celebrating the 4th of July by witnessing fireworks at the city's iconic Navy Pier, were injured after a stampede broke out in the crowd when three people were reportedly stabbed. The 3,300-foot-long pier on the Chicago shoreline of Lake Michigan draws more than two million visitors and was packed for the 4th of July celebrations. Pier officials said the entrance had to be closed before the event because it was full.

While authorities are still unsure as to what sparked the stampede, a police officer told reporters that chaos broke out when someone shouted out that there was a gun. The Chicago Police Department confirmed that 16 people had been injured after being trampled in the ensuing stampede, with harrowing footage captured at the scene showing hundreds fleeing from the pier.

Speaking of the incident, a witness at the scene told NBC, "I was walking toward the exit and all of a sudden, people were running toward me. My first instinct was to run away as well. It was just panic and everyone went along with it." Several of those trying to escape from what they believed was an active shooter scene swarmed to the waterfront restaurant, Harry Caray's Tavern, according to the Chicago Tribune. 

Anthony Guglielmi, the chief communications officer for the Chicago Police, detailed the incident in a tweet and rubbished rumors that a shooting had taken place. "CPD investigating several incidents following fireworks at Navy Pier," he wrote. "Reports of a shooting are not accurate. A man punctured his leg after running into a table, three were stabbed following an altercation on the pier, and 16 people are hospitalized after being trampled during the exit," he continued.

While the Chicago Fire Department said most of the people who had been trampled were expected to be okay, the three stabbing victims, who were said to be "young men", were reportedly taken to the hospital in serious to critical condition. The Chicago Sun-Times reported that a fight had broken out between a group of men around 10.10 pm after gang signs were flashed and that the trio was stabbed during the fight. 

One of the victims was a 15-year-old boy who was stabbed in the armpit; the second, a 14-year-old boy, stabbed in the arm and rib; and the third was a 30-year-old man who wasn't involved in the fight. He ended up with stab wounds on the face and arm.

All three have been described as being "uncooperative" with investigators and it is unclear if anyone has been arrested.