CHICAGO (CBS) — A group of Chicago police officers are talking for the first time about a daring rescue they made on Lake Michigan about a month ago.

CBS 2  showed bodycam video from January when five police officers formed a human chain to rescue a man from the icy lake. The man was trying to save a dog when he got stuck between large crashing waves and blocks of ice too big and slippery to climb over.

“It was a lot of wave action is windy,” said Seargent Alex Silvia of the Chicago Police Department. “We realized we’re actually walking out over ice to get to him, which was nerve nerve, nerve wracking, but we had to get to them quickly.”

The man who fell into the lake chose to remain anonymous, but wrote a letter thanking the officers for their heroic actions which saved his life.