Two women and three men were confirmed dead on Monday in an apparent mass drowning in Ohio after two people entered a river to help a struggling swimmer, followed by two more adults who made an ill-fated rescue attempt of their own, officials said.

According to the Delaware County Sheriff’s Office, the tragedy unfolded on Sunday night along the Scioto River at the O’Shaughnessy Reservoir, about 10 miles northwest of Columbus, Ohio, the state’s capital and largest city.

A group of at least seven people – two sets of parents, an adult male friend and two children – were relaxing along the river’s edge around sunset, some of them fishing, when one of the adults ventured into the river to swim, according to Sheriff Jeffrey Balzer.

As the swimmer began to struggle in the water, two other adults tried to assist him but began floundering themselves, leading two more adults to make rescue attempts before all five disappeared in the river, Balzer told reporters at a news conference on Monday.

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“It’s not unusual, I think, for one person to be struggling in the water, and other people attempt to save him, yet they don’t have the skills to do that, so we end up with multiple deaths,” the sheriff said.

Authorities were alerted after one of the two children ran to a nearby road and flagged down a motorist, telling the driver “his family was in the river,” Balzer said.

Emergency personnel were dispatched to the scene, where they quickly found two women and pulled them from the water. The women were pronounced dead a short time later at a local hospital, according to Balzer.

The bodies of the three missing men were recovered the next day, sheriff’s office spokesperson Tracy Whited later told news media outlets.

The sheriff said the two children, both under the age of 10, had since been placed in the care of the local family services agency.