She was cleared to return to work just over two weeks later, but for weeks afterward, she said, “The exhaustion just does not go away.”

She and Tristan Adams, another former temporary nursing assistant who worked at Brighton for two years till July, both said Brighton has long hired out-of-state agency workers. But after the outbreak began, Brighton had to go farther and farther to find agency workers — primarily from Southern states such as Louisiana, Texas, Alabama and Georgia.

For many of those agency nursing assistants, the pay was higher at Brighton — $15 an hour or more, plus travel stipends — than what they were making down South.

Yet, for many, the outbreak proved too much even for the higher pay.

“People who were up here before COVID started, they were amazing workers,” Ms. Moore said. “But they got scared and went home.”

With so many of the nursing staff either sick or refusing to come to work, at one point in early April Brighton’s managers put out their first request to the state to bring the National Guard in to help staff the building. The state, though, initially rejected the request, until May 11, when it sent 40 troops to Brighton for a week’s worth of work, primarily helping to clean the building.

Brighton hires so many people through out-of-town agencies that it began placing them in rooming houses in the area and providing a van service to take them to and from work.

The additional hiring of nursing staff in 2018 came after Brighton was named as a candidate for the federal government’s Special Focus Facilities list, the result of poor performance in state inspections beginning in 2017. The list, compiled annually by the Centers for Medicare and Medicaid Services through recommendations to state inspectors, points out the worst-performing nursing homes in the country.

Brighton declined to respond when asked whether it began hiring more nursing staff in 2018 as a result of being placed on the candidates’ list.

In 2018 and 2019, agency employees covered about 20% of nursing care hours at Brighton, according to cost report data.

Although statewide and national data was unavailable, using so much agency staffing appears to be unusual, at least in Pennsylvania.

Ms. Witt described residents, their rooms and even nonresident areas as filthy and unkempt, with residents wandering around aimlessly and a staff that was exhausted or uninterested, or both.

The floors were so understaffed, she said, that one registered nurse was responsible for three floors during the overnight, 11 p.m. to 7 a.m. shift.

“I saw [staff members] on the floor taking off their masks and gowns while they were on the floor,” a violation of protocols in place at the time, she said. “One of them said, ‘I already had [COVID-19] so why do I need to wear [protective equipment]?’”

When she asked a full-timer why COVID-19 spread so quickly through the facility, she said she was told: “Because the workers floated around the floors.”

“And other aides told me they’re on different floors every shift and won’t work in the same place for a week.”

She said that on the one day she worked at Brighton, at least four state investigators were in the building for what would become a five-day inspection. Those investigators would later report that they found violations so numerous that residents were in “immediate jeopardy.”

She said employees ran around the building that day, May 4, warning staff, “The state is on the way up!” so they could straighten up rooms or hallways and make sure everyone was wearing masks and gowns.

“Because [most of the staff] did not have on their gowns,” she said. “And as soon as the state walked off the floor, they tore them off.”

Department of Health and Human Services Inspection Report