In the days before the Life Care Center nursing home became ground zero for coronavirus deaths in the US, there were few signs it was girding against an illness spreading rapidly around the world, AP reports.

Visitors came in as they always did, sometimes without signing in. Staffers had only recently begun wearing face masks, but the frail residents and those who came to see them were not asked to do so.

And organized events went on as planned, including a purple- and gold-festooned Mardi Gras party last week, where dozens of residents and visitors packed into a common room, passed plates of sausage, rice and king cake, and sang as a Dixieland band played "When the Saints Go Marching In."

"We were all eating, drinking, singing and clapping to the music," said Pat McCauley, who was there visiting a friend. "In hindsight, it was a real germ-fest."

That was just three days before last Saturday's announcement that a Life Care health care worker in her 40s and a resident in her 70s had been diagnosed with the new virus. The news would be followed over the next few days by the first resident deaths: two men in their 70s, a woman in her 70s and a woman in her 80s.

Of the 16 deaths across the nation as of Saturday, at least 10 have been linked to the Seattle-area nursing home, along with dozens of other infections among residents, staff and family members.

A man in his 60s who died Thursday had been a visitor to the nursing home in Kirkland, public health officials announced late Friday.

As disease detectives try to solve the mystery of how exactly the coronavirus got inside Life Care, they also are questioning whether the 190-bed home that had been fined before over its handling of infections was as vigilant as it could have been in protecting its vulnerable patients against an outbreak that had already killed thousands in China and around the world.

A team of federal and state regulators planned to visit Life Care on Saturday, a move that could lead to sanctions, including a possible takeover of its management. The team will look at the home's practices, including infection control.