Sixty people who attended a recent biotech conference in Boston were rushed to Brigham and Women’s Hospital late Friday for testing for the coronavirus just hours after it was announced new suspected cases of COVID-19 originated from the gathering.

“This is a rapidly evolving situation,” Mayor Martin Walsh said at a crowded press conference in City Hall, joined by Gov. Charlie Baker and a phalanx of other local and state officials and first-responders.

The officials said a conference by Biogen at the Marriott Long Wharf downtown last week resulted in five new “presumptive positive” cases of the coronavirus. Three of those are in Boston and two in Norfolk County.

That brings the total number of presumed coronavirus cases in Massachusetts to eight as of Friday night.

That new count includes five new “presumptive positive” hits from the Biogen conference — including three sick Bostonians — on top of the three out-of-towners from the same conference who were reported on Thursday to have the virus.

These cases are “presumptive” because they’re pending final analysis by the Centers for Disease Control and Prevention to confirm that they have the virus that’s sickened more than 100,000 people around the world and killed thousands, mostly in China, but causing 14 deaths in the U.S.

Someone from Tennessee and two Europeans attended the Biogen conference and then traveled home testing positive on Thursday, officials said. The five Bay Staters were tested after Biogen identified them as having close contact with the three sick out-of-towners at the event, officials said.

Biogen issued a statement Friday night.

“We are actively working with all relevant departments of public health and hospitals to prioritize the well-being of the people who may have been exposed to COVID-19.

“We have informed employees who attended the management meeting and are symptomatic that, if they haven’t already, they will be contacted by the public health authorities to be tested and they must quarantine themselves. Additionally, these employees are being asked to isolate from the people they live with (e.g. family members, loved ones or roommates) until further notice, and these close contacts must also be quarantined until further notice.

“For meeting attendees who are not showing symptoms, individuals are being asked to stay in quarantine until further notice, and the people they live with should avoid social interaction and work from home.

“All other office-based Biogen employees and contractors in Massachusetts, Research Triangle Park, North Carolina and Baar, Switzerland are being asked to work from home until further notice.”

Mere hours after Walsh’s announcement, dozens of Biogen conference attendees headed over to Brigham and Women’s Hospital.

“The Massachusetts Department of Public Health asked Brigham and Women’s Hospital to assist in testing individuals who attended the Biogen conference in Boston last week for COVID-19,” the hospital said in a statement. “We have activated our central ambulatory screening and testing plan and will test patients outside of the hospital in the ambulance bay.”

The Brigham continued, “Our Emergency Medicine colleagues will manage the testing, and individuals will return home to await results. We do not anticipate an influx of inpatients or any impact to hospital operations or normal patient activity.”

Before that announcement, Harvard’s school of public health sent an email around to academic staff saying, “Brigham and Women’s Hospital has notified Harvard that 60 people from the Marriott Hotel in Boston are en route to the hospital to be evaluated for the Coronavirus. As a result, they are closing down Shattuck Street to ensure an orderly process. BWH has the situation under control, but please avoid that area for the rest of the day.”

A Marriott manager said that no one from the hotel is among those being taken to the hospital.

The virus continues to shut down major events, including the huge South By Southwest festival in Austin, Texas. Asked about the Boston Marathon and the St. Patrick’s Day Parade, Walsh said, “We’re monitoring the situation day-by-day,” adding the city is “not there yet” on shutting down the big events.