EMBED >More News Videos Gov. JB Pritzker extends Illinois' stay-at-home order during his COVID-19 press briefing on April 23,2020.

EMBED >More News Videos Gov. JB Pritzker said lifting the stay-at-home order completely right now could risk a deadly second wave of COVID-19 infections.

EMBED >More News Videos Gov. JB Pritzker's team of experts explain the science behind extending Illinois' stay-at-home order on April 23, 2020.

CHICAGO (WLS) -- Illinois Governor JB Pritzker announced Thursday he will extend the state's stay-at-home order through the end of May with modifications.The extension comes as Illinois health officials reported 1,826 new cases and another 123 deaths from coronavirus. There are now 36,934 patients who have tested positive for coronavirus in Illinois, including 1,688 deaths.Gov. Pritzker said the modified stay-at-home order begins on May 1 and will remain in effect through the end of the month. The original stay-at-home order was set to expire on April 30."We are in possibly the most difficult part of this journey," Pritzker said. "I know how much we all want our normal lives back. Believe me, if I could make that happen, I would. But this is the part where we have to dig in and we have to understand that the sacrifices we have made as a state are working and we need to keep going a little while longer to finish the job."Starting next Friday, it will be mandatory for all residents over the age of 2 to wear a mask in public places, such as stores and other spaces where it's not possible to maintain six feet of distance."We're not encouraging police officers to stop people and arrest them," Pritzker said of the new mask rules. "Private establishments do need to require that people who enter their establishment wear a mask."In making the case for the stay-at-home extension, Gov. Pritzker introduced some of the members of his team of scientists, whose efforts at modeling show an extension of the order was needed to stave off a second wave of infections."By heeding the governor's stay-at-home order, the population of Illinois has dramatically altered the trajectory of the epidemic in ways that we had hoped for but could not precisely predict," said Prof. Nigel Goldenfeld, University of Illinois at Urbana-Champaign."If we lifted the stay-at-home order tomorrow, we would see our deaths per day shoot into the thousands by the end of May, and that would last well into the summer," Pritzker said. "Our hospitals would be full and very sick people would have nowhere to go. People who otherwise would have won their fight against COVID would die because we wouldn't be able to help them through. No amount of political pressure would ever make me allow such a scenario for our state."But Gov. Pritzker has been pressured by state Republicans who are anxious to open things up. The new stay-at-home order comes with more flexibility for residents and non-essential businesses.Starting May 1, retail stores that are not designated as essential businesses may take orders online and by phone and offer pick-up and delivery, greenhouses and garden centers may open with social distancing measures, and there will be a phased-in reopening of state parks.Gov. Pritzker will also allow hospitals to resume some elective surgeries. Many hospitals have lost revenue that has resulted in some furloughs and layoffs."We're allowing some elective surgeries to resume for the benefit of patients and our hospital systems," Pritzker said. "But make no mistake, the first priority for our health care system continues to be the health and safety of all Illinois residents. That means preserving bed capacity for COVID patients, no matter where they come from."In a statement, Illinois House GOP Leader Jim Durkin said the governor's modifications to the order did take into account many of the suggestions from state Republicans. He said he was "pleased with today's actions" but would like to see even more done to help the state's economy. But he and others question the accuracy and how the experts are reaching conclusions."There seems to be some inconsistencies over the past few weeks over this specific modeling that he is relying on," Durkin said.Gov. Pritzker explained the modeling gets better over time because the experts are now able to use on-the-ground data. But, the governor admitted it's not an exact science."There is no crystal ball available to us, there are only estimates," Pritzker said. "Illinois is home to get some of the finest researchers in the world."Officials now expect the state's peak to be in mid-May because the infection rate is slowing down. The governor says that's a good thing because it means the peak will be lower."We are indeed doing better, and I want to make sure everybody understands," Pritzker said Wednesday. "A very good sign of how, the direction that things are going."Gov. Pritzker attributed a spike in confirmed COVID-19 cases earlier in the week to a testing milestone. The governor said Illinois performed 9,349 COVID-19 tests on Tuesday - the closest the state has come to its daily goal of 10,000 tests yet. Officials said they've been able to procure hard-to-find testing supplies."It's a complex set of things that you have to make sure you have altogether," Pritzker said. "And as you've heard, we've also lowered the bar a little bit on who can get tested now. It used to be you had to have a doctor's order. Now you don't need a doctor's order."