Kirk Webb / Lakeside Fire District via AP

In this photo provided by the Lakeside Fire District, two teenagers hang on to a dead tree after the ice on a lake started to crack in Show Low, Ariz., on Wednesday.

It was a daring mistake that two Arizona teens might never forget. On Wednesday, they ventured out onto a frozen lake in Show Low, Ariz. -- then the ice cracked beneath them.

"Luckily, they were right by a standing dead tree," Lakeside Fire District Capt. Dennis Stern told NBC News on Thursday.

For what officials believe was at least two hours, the teens clung onto the tree in the middle of the frozen lake.

Authorities say a third teen was on the bank of Fool Hollow Lake, The Associated Press reported. That individual called their parents, who in turn, contacted authorities, Stern said. After the call came in around 4:45 p.m. local time, the Show Low Fire Department worked with the Lakeside Fire District's ice rescue team to recover the stranded teens.

Related: Strangers rescue sledder who crashed through ice

The temperature was 27 degrees when the call came in, according to Stern, and plummeted to 22 degrees by the time the rescue was completed. Show Low is in eastern Arizona at 6,400 feet elevation.

"It's still early in our winter season," Stern said, noting that the ice in the area is only an inch or two thick.

The teens were treated for mild hypothermia in the hospital, Show Low Fire District Capt. Brent Mix told the AP.

"Their hands and feet got pretty cold," Mix told the AP. "It was dark by the time we got them to shore."

The ages or identities of the teens have not been released.

Related: Hunter, rescuers brave icy lake to save dog

"There is no such thing as 100 percent safe ice!" the Fond du Lac County Sheriff's Office in Wisconsin states in ice safety guidelines on its website.

"Even if ice is a foot thick in one area on a lake, it can be one inch thick just a few yards away," the guidelines warn. "It's impossible to judge the strength of ice by its appearance, thickness, daily temperature, or snow cover alone."

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