CHICAGO (CBS) — Questions persist about why North Avenue Beach was really closed on Memorial Day.

Police have insisted it was because of the heat, and not gang violence. But now, 9-1-1 calls made that day seems to suggest concerns about the crowds.

LISTEN: Newsradio 780’s Michele Fiore reports

“We need police at the outer drive at North Avenue. There’s three lanes of traffic at the Outer Drive that are stopped, for miles,” one woman says.

The dispatcher asks: “Do you know what’s going on there?”

“Yea, it’s North Avenue. It’s Oak Street Beach … and it’s summer time.  That’s what’s going on,” the caller responds.

Another caller describes her concern for those leaving the beach: “There’s thousands of people on that beach, and when they all come out of there, it’s gonna be a nightmare.”

Sources tell CBS 2 that North Avenue Beach was closed because of fights at Oak Street Beach. The two are connected by direct access.

Police say heat-related illness was the reason.