The most recent uptick in positive cases across the Washington region has hit the D.C. Fire and Emergency Medical Services (FEMS) Department particularly hard, prompting longer shifts for some first responders who’ve had to fill in for out-of-service employees.

As of Tuesday, 363 — about 18% — of the 2,039 D.C. FEMS employees were quarantining due to COVID-19 cases or exposures, according to the department. Of those, 309 have reported a positive COVID-19 test, while 54 staffers are quarantining due to a close contact. Over a four-day period, from Christmas Eve to Tuesday, a total of 190 workers tested positive.

Additionally, there have been multiple reports of ambulance delays due to long hospital wait times and a high volume of non-emergency 911 calls — which have gone up during the holidays.

Dave Statter, a local fire and EMS reporter, posted audio recordings of 911 calls over an 11-minute period on Tuesday morning, when three ambulances were sent across the city to respond to calls. At one point, a staff member with the Office of Unified Communications (OUC) told a first responder to continue on their route, as no other vehicles were available.

“Copy, no other EMS in the whole city available. Thank you,” the first responder replied.

More than 1,800 staffers in the department have been fully vaccinated. Of the 429 positive cases reported since October, when the District’s vaccine mandate was instated, 326 have been fully vaccinated members. There’s been a 41% positivity rate — or 96 cases — among the 233 unvaccinated members of the department.

In September, some firefighters pushed back against the city’s vaccine mandate, arguing that it would cause a staffing crisis within the department. Most unvaccinated first responders have cited a religious exemption.

When first responders test positive while on duty, their unit is placed out of service while the department works to fill the shift and get it back on the street — a process that can take anywhere from 30 minutes to several hours, according to Jennifer Donelan, a spokesperson for FEMS.

“Our Department operates in four 24-hour shifts, so not everyone works at one time,” Donelan told DCist/WAMU over email. “When there is a vacancy, other members return to work to fill the vacancies. That does mean our members are working long shifts.”

Fire trucks that respond to 911 calls provide medical treatment while waiting for an ambulance, Donelan added. “Our system is designed this way to get you help quickly.”

Donelan said the department has been “rising to the challenge” of the spike in numbers and that they have a contingency plan in place based on CDC guidelines. “We are answering all calls for service 24 hours a day, seven days a week,” Donelan said. “That has not changed since this most recent surge began.”

Chief John Donnelly tweeted a statement on Sunday thanking the off-duty officers who have filled in shifts. The department has had to fill more than 100 vacancies over the past week, he said.

So proud of #DCsBravest over the holidays, as the COVID-19 has moved through the Department over 100 24 hour vacancies have had to be covered each day. For each one of these, 2 off-duty FF have had to report for 12 hours each. Thank you to each of them and their families.

— DC Fire & EMS Chief (@FD_Observer) December 27, 2021

Deputy Mayor for Public Safety and Justice Chris Geldart told NBC4 the numbers are “serious” but not yet “critical.”

“When we do lose and engine like that, there’s a backup right away to it and a backup to that,” he said. “May that extend our time a little bit? Potentially. But there’s a lot of backups that go into play with that so that we don’t miss a call, and we don’t put anybody in jeopardy.”

“While we are still very much in the midst of this and we recognize the gravity and historical nature of what is unfolding, we simply couldn’t be prouder of our members,” Donelan told DCist/WAMU.

This story has been updated to clarify the staffing process within the DC fire and EMS department and with additional comment from Jennifer Donelan.