AUSTIN, Texas (AP) — Exxon Mobil Corp. has reported inadvertent emissions of large amounts of pollutants at its flagship refinery near Houston.

Officials at the Baytown refinery reported a leak in a heat exchanger tube on Tuesday prompted them to shut down a flexicoking unit that separates heavy oils into fuels.

In their report to the Texas Commission on Environmental Quality, the officials reported that the shutdowns resulted in releases of hydrogen sulfide, nitrous oxide, sulfur dioxide and carbon monoxide exceeding the plant's permit limits.