JOHANNESBURG -- The coronavirus storm has arrived in South Africa, but in the overflowing COVID-19 wards the sound is less of a roar than a rasp.

Medical oxygen is already low in hospitals at the new epicenter of the country's outbreak, Gauteng province, home to the power centres of Johannesburg and the capital, Pretoria. Health Minister Zweli Mkhize, visiting a hospital Friday, said authorities are working with industry to divert more oxygen their way.

Some of the hospital's patients spilled into heated tents in the parking lot. They lay under thick blankets in the middle of winter in the Southern Hemisphere, with a cold front arriving this weekend and temperatures expected to dip below freezing.

South Africa overnight posted another record daily high of confirmed cases, 13,674, as Africa's most developed country is a new global hot spot with 238,339 cases overall. More than a third are in Gauteng.

"The storm that we have consistently warned South Africans about is now arriving," Mkhize said this week.

A nurse at Chris Hani Baragwanath Hospital -- the third largest hospital in the world with more than 3,000 beds -- painted a bleak picture, saying new patients with the virus are now being admitted into ordinary wards as the COVID-19 ones are full.

"Our hospital is overloaded already. There has been an influx of patients over the last two weeks," the nurse said, speaking to The Associated Press on condition of anonymity because they were not authorized to give interviews.

More and more colleagues at the hospital are testing positive daily for the virus, the nurse said, "even people who are not working in COVID wards."

Already more than 8,000 health workers across Africa have been infected -- half of them in South Africa.

How the country struggles to manage the pandemic will be amplified in other nations across Africa, which has the world's lowest levels of health funding and health staffing.

The continent as of Friday had 541,381 confirmed cases, but shortages in testing materials means the real number is unknown.

South Africa's surge in cases comes as the country loosens what had been one of the world's strictest lockdowns, with even alcohol sales banned until June 1. Now restaurants have sit-down service and religious gatherings have resumed. The economy was hurting and needed reopening, authorities said.

But nervous officials in Gauteng province have called for stricter lockdown measures to return. On Friday, Gauteng Premier David Makhura announced he had tested positive with mild symptoms.

"We must double our efforts," he said in a statement, urging people to wear face masks, wash their hands and distance themselves.

Warning signs keep flashing. Hospital beds in all provinces could be full within the month, the health minister said this week. On Friday he said a team is looking at 2,000 additional beds for field hospitals in Gauteng.

In addition to the bed shortage, many hospitals are grappling with limited oxygen supplies to treat patients with the respiratory disease.

Guy Richards, director of clinical care at Charlotte Maxeke Hospital in Johannesburg, told the AP they are extremely worried.

"Even a big hospital like ours has difficulty supplying sufficient amounts of oxygenation for our patients. The same thing is happening at Helen Joseph (Hospital), and this is a major problem," he said.

At the field hospital in the Nasrec Expo Center in Johannesburg none of the 450 beds have oxygen, said Lynne Wilkinson, a public health specialist who is part of a volunteer effort that's calling for 100 oxygen concentrators. The purity and volume of oxygen is lower in the portable and usually temporary devices.

Sourcing them is a problem because they're bought up by the private sector, even private individuals, she told the AP: "They keep them at home."

Eight hundred new beds will be built at the field hospital, and the health minister on Friday said the facility would receive 1,000 "oxygen points." But that will take weeks, Wilkinson said.

While there's amazing camaraderie among volunteer health workers, "the patients are scared, very, very scared," she said. "If you can't breathe and you're not sure you're able to get oxygen, it's a very anxiety-provoking situation."

Tshwane District Hospital, which the health minister visited Friday, is now devoted completely to COVID-19 patients, said Veronica Ueckermann, head of the COVID-19 response team at Steve Biko Academic Hospital, which includes Tshwane District Hospital.

"Currently we are stretched but we are still coping in terms of our wards, our sisters and doctors are working extremely hard," she said.