HOLLAND, Mich. (AP) — Authorities say the search for two teenage boys who went missing while swimming in Lake Michigan has become a recovery effort.

Authorities who gathered at Holland State Park in western Michigan say four teenage boys were swimming 7:30 p.m. Wednesday when they were dragged out by strong currents and high waves. Two boys managed to get out of the water, while boats and helicopters tried to rescue the others.

Before 11 p.m., authorities said the water was too rough and they temporarily halted the search. But the U.S. Coast Guard says its crews actively searched through the night. The Ottawa County sheriff’s department returned to the water Thursday.

The department has identified the missing boys as 14-year-old Vincent Green and 17-year-old Christopher Mimis, both of the Holland area.