The annual Ice Fishing Derbyfest on Sebago Lake in southern Maine was canceled Saturday after seven people and a number of automobiles, ATVs and snowmobiles went through the ice.

A day earlier, a state game warden riding an ATV also went through the ice on Sebago Lake.

Major Gregg Sanborn, deputy chief game warden, called the ice on Sebago Lake extremely unsafe.

“Anyone who wants to go out onto ice, particularly in southern Maine, should think twice before risking their lives and possibly the lives of others,” he said in a statement. “In other parts of the state, check often before venturing too far out and go back to shore if you’re unsure about its thickness.”

Saturday’s above-average temperatures contributed to melting ice not only on Sebago Lake but also other Maine waterways. Two vehicles went through the ice in separate incidents in the Millinocket area on Saturday night.

A snowmobile driven by Danny Gallant of East Millinocket partially broke through the ice on Millinocket Lake, according to Maine Warden Service Sgt. Ronald Dunham. Gallant and a passenger fell through the ice, into the water, but both were able to get out and walk on the ice. Neither Gallant nor his passenger, who was not identified, was injured.

An ATV driven by Stephen Davenport of Presque Isle went through the ice shortly before 8 p.m. Saturday on South Twin Lake. Davenport also was able to get out of the water and was unharmed.

Also on Saturday, a 63-year-old man drove his car into an ice pressure ridge on Damariscotta Lake and it broke through into 40 feet of water.

Henry Lee was driving his 2006 Chevrolet Impala on Damariscotta Lake when it went into the water, according to Maine Game Warden Joey Lefebvre. Lee heard the ice breaking under his vehicle, opened its door, and jumped from the vehicle as it was going down, the warden said. As of Saturday evening, the vehicle remained in the lake.

Although the incidents of the weekend did not involve tragedies, the Maine Warden Service urged people to use extreme caution on Maine’s waterways. Ice is thinner than usual because of above-average temperatures, but conditions also are changing due to pump stations drawing down water on numerous waterways.

In the Friday afternoon incident, Gary Allen, a Maine warden, was riding an ATV near Raymond Beach when his vehicle began to go through the ice. Allen, who was wearing what is known as a “float coat” to protect him from the cold water, was able to get out of the water by kicking his feet and sliding onto the ice. His ATV sank in about 40 feet of water.