DANNEMORA, N.Y. — Two murderers who escaped from a prison by cutting through steel walls and pipes remain on the loose as authorities investigate how the inmates obtained the power tools used in the “Shawshank Redemption”-style breakout.

Gov. Andrew Cuomo said the escape over the weekend was a “sophisticated plan” and announced a $100,000 reward for information leading to men’s capture.

David Sweat, 34, was serving a sentence of life without parole for the 2002 killing of a sheriff’s deputy. Richard Matt, 48, had been sentenced to 25 years to life for kidnapping, killing and dismembering his former boss in 1997.

“These are killers. They are murderers,” the governor said. “There’s never been a question about the crimes they committed. They are now on the loose, and our first order of business is apprehending them.”

Officials gave no details on how the men managed to avoid detection while cutting their way out. “They had to be heard,” Cuomo said in a press release.