UPDATE: Several aldermen confirm the lakefront is closed to the public, effective Thursday morning.

CHICAGO (CBS) — Visibly frustrated with reports of gatherings throughout Chicago, Mayor Lori Lightfoot delivered a stern warning to those who continue to get together during the COVID-19 pandemic: We will shut it down and you may be arrested.

“Stay at home. Only go out for essentials. You have to readjust your thinking. Be smart,” Lightfoot said. “Not only will our police be deployed to shut them down if you are not abiding by these orders we will be forced to shut down the parks and lakefront. The situation Is deadly serious and we need you take it deadly seriously.”

Lightfoot added that spending long periods of time outdoors, anywhere, is not allowed. And neither is going into closed spaces, like playgrounds.

“You cannot go on long bike rides. Playgrounds are shut down. You must abide by the order. Outside, is for a brief respite, not for 5Ks. I can’t emphasize enough that we abide the rules.”

Chicago Park District CEO Mike Kelly said outside spaces are open but need to be used judiciously.

“The parks and open space are here for your enjoyment. But keep your distance. If someone is passing by, step aside and let them through,” Kelly said.

Doctor Allison Arwady from the Chicago Department of Public Health said the orders have a specific purpose and need to be followed.

“We don’t have a vaccine. We don’t have a treatment. Chicago has an A for preparedness. But we are planning for some real worst case scenarios,” Arwady said. “The next two to three weeks will be the most important time to do everything we can to flatten that curve. Doing that is what will keep our hospitals going.”

Interim Police Superintendent Charlie Beck issued the strongest warning about being out with others.

“The public health order is not an advisory. It is a mandate. If you violate, it your are subject to a fine of $500. If you continue to violate it, you will be subject to arrest,” Beck said.

No longer three warnings. Interim #CPD Supt. Charlie Beck says people at large gatherings will now only get one warning to disperse. Then – a ticket. ⁦@cbschicago⁩ pic.twitter.com/WBDUp1S3ni — Dana Kozlov (@DanaCBS2) March 25, 2020

Beck also answered questions about reports of CPD officers who said they are working in unsafe and unsanitary conditions with the threat of being exposed to the coronavirus. Several officers have tested positive for COVID-19.

“Cleaning has increased in all stations. We have increased our cleaning schedule. And the cleaning schedule of cars,” Beck said.

But Lightfoot reiterated that not following the stay at home order will bring serious consequences.

“At worst, we will take you into custody.”