LIVONIA, N.Y. (AP) — Authorities have released the names of the two men who haven't been seen since they ventured onto a frozen western New York lake on a snowmobile.

The Livingston County Sheriff's Office says Christopher Copeland, of Livonia, and Jason Fluet, of Rochester, both 40, went snowmobiling on the north end of Conesus (kun-EE'-shuhs) Lake early Saturday morning.

A family member alerted the sheriff's office early Sunday morning that the men hadn't returned since setting out from Copeland's lakeside home in Livonia, 20 mile south of Rochester. A search launched Sunday turned up a snowmobile's tracks on the ice and two helmets in the lake.

Sheriff Thomas Dougherty says the two men were riding on the same snowmobile.

The search is set to resume Wednesday.