iStock/sshepardBY: MEREDITH DELISO, ABC News(MADISON, Wisc.) — Wisconsin Gov. Tony Evers declared a new public health emergency Tuesday amid an “alarming” increase in COVID-19 cases since college campuses reopened.“We continue to learn more about this virus, but what we do know is that we are facing a new and dangerous phase of the COVID-19 pandemic here in Wisconsin,” Evers said in a statement. “We are seeing an alarming increase in cases across our state, especially on campus. We need folks to start taking this seriously, and young people especially.”Due to the increase in cases, the governor also extended a statewide mask mandate, which was set to expire next week, through Nov. 21.We are facing a new and dangerous phase of the COVID-19 pandemic here in Wisconsin. We are seeing an alarming increase in cases across our state, especially on campuses. This is serious and we need your help.— Governor Tony Evers (@GovEvers) September 22, 2020New cases have had “unprecedented, near-exponential growth,” Evers’ statement said, noting that from Aug. 31 to Sept. 21, the number of daily new cases rose from 678 to 1,791 — a 2.6-fold increase in three weeks. Within the past month, 18- to 24-year-olds have had a case rate five times higher than any other age group in the state, officials said, with the increase apparently driven by social gatherings.The governor’s office pointed to the state university system, whose 13 universities have all reopened for in-person learning this fall, as a driver in the increasing numbers. Last week, six out of eight Wisconsin cities listed among the top 20 cities in the U.S. where COVID-19 cases were rising fastest are home to University of Wisconsin System campuses, officials said.Tensions have been escalating in Dane County, home to the flagship campus UW-Madison. Earlier this week, Dane County Executive Joe Parisi called on the university to go virtual amid rising cases in the county.“Today, as our state surpasses the 100,000 case mark, we find ourselves in the midst of an unprecedented surge in COVID-19 cases fueled largely by the University System’s decision to return to in-person classes,” Parisi said in a statement, which noted that the rate of infection in the county was 3.5 times higher on Sunday than two weeks prior.“COVID-19 is here, it’s spreading, and barring a major course correction this region and state are in store for countless tales of unnecessary human suffering,” he said.Since Aug. 24, more than 2,650 confirmed cases of COVID-19 have been tied to the campus, according to data on UW-Madison’s website.The university, which shifted to virtual learning for two weeks on Sept. 10 and quarantined two dorms amid rising cases on campus, responded by asking the county to partner with them in enforcing safe behavior off-campus.“We know these gatherings can lead to the spread of COVID-19 but UW-Madison does not have jurisdiction to shut down gatherings in off campus areas,” Chancellor Rebecca Blank said in a statement. “Until those agencies with enforcement authority take additional action, we shouldn’t expect to see a rapid decline in cases in Dane County.”Copyright © 2020, ABC Audio. All rights reserved.