Yonkers Fire Department Deputy Chief Kevin Ford says nobody was injured in the mishap Monday.
Ford says the truck's brakes gave way while it was stopped to make a delivery. The driver wasn't in it at the time.
Ford says the 4,000-gallon tanker descended a hill, hit a car and struck the building. He says the vehicle then tilted onto its side.
The building wasn't structurally damaged.
Ford says a hazmat team has stopped the leak. He says the tanker company is sending workers to right the tanker and tow it away.
The company's name hasn't immediately been disclosed.