New York City ? Prosecutors opened a criminal investigation Tuesday into the blaze that killed two firefighters at a ground zero skyscraper that had a broken water supply system as it was being dismantled.

The defunct standpipe pumped thousands of gallons into the basement, leaving firefighters without enough water to fight the fire that started Saturday on the 17th floor.

“Nobody at this point knows whether that was a contributing factor to the two tragic deaths or not. That’s what an investigation is for,” Mayor Michael Bloomberg said.

Manhattan District Attorney Robert M. Morgenthau and State Attorney General Andrew Cuomo said their offices each would investigate the cause of the blaze.

Meanwhile, several agencies sought to deflect blame for the building’s failed water supply system, the response to the fire and who was responsible for inspecting the tower.