Health care workers worried about a shortage of supplies, especially masks the U.

S.

With a stockpile of about 12,000 ventilators.

The call going out for President Trump to use the Army Corps of Engineers to quickly create new medical facilities.

Here's NBC's Marci Gonzalez tonight, with the number of covert 19 cases rising hospitals across the country preparing for a potential crush of patients, some constructing tents to handle possible overflow.

Health officials working around the clock on plans to keep the health care system from being pushed to the limits.

If we have a worst case scenario, we've got to admit it.

We could be overwhelmed.

Well, we're gonna have a worst case scenario.

I don't think so.

I hope not.

We checked in with hospitals from coast to coast, thes California medical centers, conducting drills.

We're not seeing too big of an influx with right now, but a much different story tonight.

It's South Shore Health in Massachusetts, where they're seeing high volumes of patients with respiratory symptoms.

We have to assume that when they're coming in, that all of them could have cove it 19 now, of course they don't.

But we have to be very careful to make sure we maximize our personal protective equipment because we cannot afford to get infected.

In New York Governor Andrew Cuomo, warning it could be just weeks before the health care system there is overwhelmed, pointing to a shortage of critical ventilators needed to treat the most vulnerable patients in intensive care units.

They are scarce, and you can't find available ventilators, no matter how much you're willing to pay.

And while President Trump says masks are now being made by the millions in Ohio, a nurse's union raising concerns about the availability of protective gear, we are very concerned that when this virus peaks that we have enough of this equipment for our nurses to take care of our patients properly.

And tonight, New York's governor is calling on President Trump to mobilize the Army Corps of Engineers to convert places like military bases and college dorms into temporary medical centers.

Tom All right, Marcie.

Thank you.

Hi, everyone.

George Stephanopoulos here.

Thanks for checking out the ABC News YouTube channel.

If you'd like to get more video show highlights and watch live event coverage, click on the right over here to subscribe to our channel.

And don't forget to download the ABC News after breaking news alerts.

Thanks for watching.