The Washington Nationals canceled workouts Monday morning, General Manager Mike Rizzo announced in a statement, citing a lag in testing results that could put players, coaches and staff members in danger of contracting the novel coronavirus.

“Per MLB’s protocol, all players and staff were tested for Covid-19 on Friday, July 3rd. Seventy-two hours later, we have yet to receive the results of those tests,” Rizzo said in his statement. “We cannot have our players and staff work at risk. Therefore, we have canceled our team workout scheduled for this morning. We will not sacrifice the health and safety of our players, staff and their families.

“Without accurate and timely testing it is simply not safe for us to continue with Summer Camp. Major League Baseball needs to work quickly to resolve issues with their process and their lab. Otherwise, Summer Camp and the 2020 season are at risk.”

The Nationals have shut down training until they receive those Friday results. When they do, they will assess how to move forward.

Summer training began Friday, once the first wave of players passed intake screening for the coronavirus. But since then, there have been widespread doubts about baseball’s testing model, which were raised by Nationals closer Sean Doolittle on Sunday. While speaking with reporters around noon, Doolittle had yet to receive results for a Friday test. He had, however, been tested again, and the unprocessed samples were piling up.

MLB is using one lab in suburban Salt Lake City to process tests performed every other day for all players, staff members and coaches of 30 clubs. The return plan hinges on frequent results to mitigate possible spread of the virus. But there is skepticism about whether using just one lab to process so many samples can work.

Washington’s canceled workout is one example of the model’s fragility. Two Nationals players tested positive for the coronavirus during intake screening last week. They were never at the team facility, according to Manager Dave Martinez, but others who came into contact with them have been unable to join workouts, according to people with knowledge of the situation.

“Even the intake tests, there were clubs that couldn’t work out as a team on Friday because they were still waiting for our results,” Doolittle said Sunday. “We got our results at like three in the morning, so we all just kind of set our alarms and then we all got the notification when we woke up and we were like, ‘Okay, we can have practice.’ ”

There was similar uncertainty Monday morning, then the announcement from Rizzo. According to MLB’s operations manual for 2020, intake tests were expected to be turned around in 24 to 48 hours. After that, with the every-other-day testing, results are supposed to arrive in approximately 24 hours.

But that didn’t happen in the first testing cycle. And now the Nationals won’t continue without the necessary and promised data.

“Spring training’s only three weeks long. You’ve got to have those days. You need every day to try to get ready,” Doolittle said Sunday. “So as the season moves forward, as we continue spring training, especially once we start traveling, those results got to be back. That’s one of the biggest things. … There were a lot of guys that were on the fence that decided to try to play, to see how this was going to go, because we were going to have our results within 48 hours.

“So hopefully that’s something that we can address and improve moving forward.”