Two neighbors fishing together on a central Minnesota lake died, with one not found until the next day inside an ATV well below the surface, authorities said.

According to the Morrison County Sheriff’s Office, Wayne Vaverek, 68, and Leonard Sanoski, 71, were fishing together Sunday, and family members alerted authorities after they failed to return home.

Emergency responders located open water west of the Big Island near the middle of the lake. Vaverek’s body was spotted on the ice near the open water’s edge.

The responders halted their search for Sanoski until Monday morning and located his body in the enclosed cab of the side-by-side ATV, which was in about 40 feet of water.

“This incident took place on a pressure ridge,” the Sheriff’s Office said in a statement announcing the deaths on Fish Trap Lake, located about 5 miles north of Cushing, Minn., which is northwest of Little Falls.

The ridge was approximately 200 yards long running north to south and approximately 75 yards wide east to west. These ridges form when the air temperature warms the ice and water rises in the cracks and freezes over.

Orange cones were left at the ridge as a warning to others to stay away from the area, the statement continued. “The ice conditions vary throughout the lake and should not be considered 100 percent safe,” the Sheriff’s Office said.