Hundreds of teenagers ran amok in downtown Chicago for a second night Saturday, smashing car windows, assaulting drivers, and prompting a major police response.

According to local news reports, the unruly mob massed outside Millenium Park — a waterfront park that is one of the city’s most popular tourist attractions — and became agitated when they were denied entry by police and security officials. Officials were only allowing visitors under 21 access to the park if they were accompanied by an adult.

Shots were fired on at least one occasion and news crews covering the chaos were forced to flee the scene out of fear for their safety. Police also had to escort tourists visiting the park back to their cars in a nearby parking garage. At least two teens were wounded in the gunfire.

One woman told Chicago’s Fox affiliate that the teens jumped on her car, smashing the windshield, and assaulting her husband, who was in the driver’s seat. The Chicago Transit Authority was forced to divert several subway trains from the area until police could regain control of the situation.

Saturday’s chaos comes after a similar gathering of teenagers at a downtown Lake Michigan beach, the 31st Street Beach, Friday evening. Hundreds — perhaps as many as 1,000 according to local media reports — of teens showed up there after posts promoting a teen “meet-up” circulated on social media.

The crowds Friday only began to thin after a 14-year-old boy was shot in the thigh. An eyewitness told Chicago’s NBC affiliate that police on the scene were vastly outnumbered.

“It was a lot of cops here, but they were still outnumbered,” the unnamed witness said. “There were so many teenagers that showed up, and they tried to keep the peace and keep them under control.”

“It’s heartbreaking, kids fighting, chasing each other, some of them got guns,” he added.

In a statement regarding Friday’s incident, Chicago police said it was monitoring the situation throughout the city over the weekend and deploying “resources as necessary so residents and visitors can safely enjoy the city, including our beaches and lakefront area.”

“Last night, CPD monitored activity happening across the city and officers were in place to quickly respond to active incidents and large gatherings,” the statement said. “We will continue to have sufficient resources in place as we work to strengthen safety in every neighborhood.”