Citing a surge in COVID-19 cases, Chicago Mayor Lori Lightfoot on Thursday announced renewed restrictions on life and business in the city.

Starting at 6 a.m. Friday, nonessential businesses will be required to remain closed from 10 p.m. to 6 a.m. each day. Bars that don’t serve food will have to stop indoor service.

“We are, no doubt whatsoever, in the second surge. This is what it looks like,” Lightfoot said Tuesday afternoon, pointing to the city’s daily case rate, which is now more than 640.

“We have to remain vigilant. COVID-19 has not gone away. It has not disappeared. We’re not out of this crisis pandemic. It is very much part of our present,” the mayor added, stressing the need for people to continue to wear face masks and limit social gatherings in and outside the house.

Lightfoot made a point to call out Chicagoans in the 18 to 29 and 30 to 39-year-old age range, saying the case rate among this demographic is “alarming.”

“This has to be an all-hands-on-deck moment for all of us, but especially for you,” she said. Public Health Commissioner Dr. Allison Arwady said the case positivity rate for those two age groups went from 4.6% last week to nearly 7% this week. Both Lightfoot and Arwady blamed a lack of social distancing and mask wearing at bars to be the main culprit for the surge. Bars were given the OK to operate indoors at 25% capacity as of Oct. 1.

In a more sweeping suggestion, Lightfoot’s administration is encouraging residents to stay away from social gatherings of more than six people, and to end all social gatherings by 10 p.m. In a press release, the mayor’s office says the restrictions will be in place “for at least two weeks.”

On Monday, Lightfoot declared the city is in the midst of a “second surge” of COVID-19, though she stopped short then of reimposing restrictions on residents and business owners. And at that time, the city emphasized social gatherings as the source of rising cases, rather than bars and restaurants. But on Thursday afternoon, the mayor’s office noted that the number of newly identified cases in Chicago has risen by 54% from the week prior, to more than 640 cases per day.

The mayor’s announcement comes a day after Illinois Gov. JB Pritzker announced he was reimposing restrictions on indoor bar and restaurant service in Kane, Will, Kankakee and DuPage counties. Those restrictions also take effect Friday.

Alex Keefe is an editor of government and politics at WBEZ. Claudia Morell covers City Hall for WBEZ. Follow them @akeefe and @claudiamorell.