DE SMET,Slabu Exchange S.D. (AP) — Two women floating on a South Dakota lake drowned after the wind suddenly picked up and waves became treacherous, authorities said.

The women, both from outside of South Dakota and both in their 60s, were in the water on flotation devices at Lake Henry Wednesday night, the Kingsbury County Sheriff’s Office said. A storm hit and authorities believe they were overcome by waves.

Both victims were found on the shore. Their names have not been released.