LOS ANGELES — Los Angeles ambulance workers have been told to stop transporting some patients with extremely low survival chances to hospital, and to limit oxygen use, as record Covid cases overwhelm medical resources.

California has emerged as the latest epicenter of the US coronavirus pandemic, with nearly 4,000 deaths in the last two weeks alone, and hospitals bracing for another surge expected from the holiday period.

In Los Angeles, where packed hospitals have been turning away ambulances, medics were Monday instructed not to transport adult cardiac arrest patients if they cannot be resuscitated in the field.

The county’s Emergency Medical Services (EMS) agency also issued a directive for ambulance crews to save oxygen supplies by only administering to patients with severely low levels.

Local EMS agency head Marianne Gausche-Hill told CBS that medics were “not abandoning resuscitation” in the field, but that transporting patients with “very poor outcomes” who cannot be resuscitated could “impact our hospitals.”

California was initially praised for its handling of the pandemic in March, but is now reeling. In the past seven days it has recorded more than twice as many cases as any other state, placing a huge strain on resources.

“Many hospitals have reached a point of crisis, and are having to make very tough decisions about patient care,” said Los Angeles County director of health services Christina Ghaly.

Firefighters trained as paramedics have been temporarily called up to assist hospital staff, while army engineers were drafted in to bolster straining oxygen delivery systems at six hospitals.

“We’re likely to experience the worst conditions in January that we’ve faced in the entire pandemic — and that’s hard to imagine,” Los Angeles County public health director Barbara Ferrer said Monday.

Positive Covid cases in the nation’s most populous county had doubled in just over a month to 800,000, she said, with more than one-in-five who get tested currently positive.

“The steepness of this line is frightening, and its implications for our healthcare system, our health care workers, and all the people we care about,” she added, referring to the data.

Vaccinations have begun for emergency healthcare workers and the most vulnerable in California, but Governor Gavin Newsom said Monday the process had “gone too slowly.”

Barely one-third of 1.3 million delivered vaccines have been administered so far.