DENVER (KDVR) First responders and law enforcement were investigating a death at the Cherry Creek Reservoir in Colorado on Tuesday afternoon of what potentially was an ice fisherman who had fallen through the ice.

The matter was reported by the Arapahoe County Sheriff’s Office, which said it was one scene with Cherry Creek State Park rangers and South Metro Fire Rescue at about 3:10 p.m.

The Arapahoe County Sheriff’s Office said a pair of fishermen were heading out onto the water near the spillway on Tuesday when they saw a cooler floating about 50 to 75 feet offshore. They went out to drag it to shore, and after moving it, found there was a 65-year-old male body grabbing the cooler.

The fishermen still dragged the cooler and body to shore, and informed officials.

The sheriff’s office said the man appeared to have been ice fishing and fell through the ice. The South Metro Fire Rescue dive team was on scene, and ice fishing gear and equipment was recovered from the water. The sheriff’s office said it was still in the preliminary stages of the investigation, and that they were still looking for any other bodies that may be in the reservoir.

The agency also said it has “no idea” how long the body was in the water, with a public information officer noting it could be anywhere from one day to five days. The agency also is not sure what happened to lead to the man’s death.

Colorado Parks and Wildlife’s Kara Van Hoose said this time of year is a dangerous time for ice fishing.

“Tricky time of year to ice fish,” Van Hoose said. “Really dangerous to be on reservoirs right now.”

She said the ice during days like Tuesday can rapidly change due to the warm air mass.

The reservoir has many areas to it, and the sheriff’s office said the body was found near the spillway. The area is popular for its swim beach in the summer, as well as its year-round hiking trails and other facilities.