O'FALLON, Mo. — Missouri’s health director issued a dire warning Monday after photos and video showed Memorial Day weekend revelers partying close together.

One video on social media showed a crammed pool at Lake of the Ozarks, with people lounging and playing close together, without masks.

Missouri Department of Health and Senior Services Director Randall Williams said in a statement that behavior like what was seen at the lake could have “long-lasting and tragic” results.

The lake draws people from as far away as Arkansas and Iowa. It’s also an especially popular spot for travelers from St. Louis city and county, which combined account for more than half of Missouri’s 11,988 confirmed cases of COVID-19, and more than two-thirds of the 681 deaths.

Bars, restaurants and hotels at Lake of the Ozarks also had big crowds, and they weren’t alone. In Hannibal, Mark Twain’s hometown and a popular regional tourist attraction, people could be seen sitting shoulder-to-shoulder inside and out at downtown bars and restaurants over the weekend.

Republican Gov. Mike Parson allowed Missouri businesses and attractions to reopen May 4, but the state order requires 6-foot social distancing through at least the end of May. The order leaves it up to local and state health officials to enforce social distancing. It wasn’t immediately clear if Camden County, the lake county that draws the biggest crowds, planned any action.