• Paramedics and emergency service providers are facing "extreme stress" as the Covid-19 pandemic drags on, Acadian Companies CEO Richard Zuschlag told CNBC.
• "This coronavirus has just been very difficult for us because we don't really know when it's going to end," Zuschlag said.
• "I find a lot of our medics are taking early retirement because they're concerned about catching the Covid disease," he added.

Now stretching into its ninth month, the coronavirus pandemic is putting significant strain on paramedics and emergency medical technicians across the U.S., the CEOs of ambulance companies told CNBC on Friday.

"There's a huge shortage of paramedics nationwide, whether it be for the public fire departments or the private ambulance companies," Richard Zuschlag, chief executive of Acadian Companies, said in a "Squawk on the Street" interview. "It's an extreme problem right now."

Based in Lafayette, Louisiana, Acadian provides medical transportation services in its home state, as well as Texas and Mississippi. In his nearly 50-year career providing ambulance services, Zuschlag said hurricanes Katrina and Rita were the "most severe" disasters to which they have responded.

However, the pandemic presents a different kind of challenge. "This coronavirus has just been very difficult for us because we don't really know when it's going to end," he said.

"It puts an extreme stress on the medics, and I find a lot of our medics are taking early retirement because they're concerned about catching the Covid disease," he said. And, he added, there are worries among his employees about bringing the virus home to their families.

Zuschlag's comments come as the nation's seven-day average of new coronavirus cases was at record high of 179,473, according to a CNBC analysis of data compiled by Johns Hopkins University. There also are more than 100,000 patients currently hospitalized with Covid-19, the most during the pandemic, according to the COVID Tracking Project.

More than 2,800 new deaths in the U.S. have been recorded in back-to-back days, Hopkins data shows. The elevated totals follow remarks earlier this week from the director of the Centers for Disease Control and Prevention, Dr. Robert Redfield, who said "December and January and February are going to be rough times."

"I actually believe they're going to be the most difficult in the public health history of this nation, largely because of the stress that's going to be put on our health-care system," Redfield said.

The nation's paramedics are experiencing it firsthand. The American Ambulance Association warned in a letter to the Department of Health and Human Services, obtained by NBC News, that "the 911 emergency medical system throughout the United States is at a breaking point." It is calling for more financial aid to help weather the latest surge.

"All of our workforce ... are incredibly tired, stressed. The extra work that they have to do is very taxing, both mentally and physically, and there's a lot of turnover," Randy Owen, CEO of Global Medical Response, also said Friday on "Squawk on the Street." The Colorado-based company provides fire services and medical transportation across the U.S. and abroad.

In Louisiana, in particular, the uptick in coronavirus cases has again caused challenges with hospital capacity, Zuschlag said. The state health department said that in hospitals in the Lafayette area, where his company is based, nearly every intensive care unit bed was in use as of Wednesday.

Sometimes, he said, the closest hospitals are unable to accept the patients the company is carrying. "So we are forced to transport patients as far as 100 to 200 miles away to another hospital that can take them, and it just seems to continue to be a problem," he added. "I know the vaccine will help. We just don't know when this will slow down."