DALLAS (AP) — Exxon Mobil has released pollutants into the air from a refinery that was caught in the storm pounding the Texas Coast.

The oil giant told regulators that a floating roof over a tank at its refinery in Baytown, Texas, oil refinery partially sank in during the heavy rainfall, releasing emissions.

Other emissions were released during the planned shutdown of the refinery before the arrival of Harvey, which was then a hurricane but later downgraded to a tropical storm.

In initial filings this week with the Texas Commission on Environmental Quality, the company did not identify the chemicals that were released.

David Gray, a spokesman for the Environmental Protection Agency, said the company reported that it released 15 pounds of benzene due to damage from the storm. The EPA classifies benzene as a carcinogen.

“This is an unprecedented storm, and we have taken every effort to minimize emissions and safely shut down equipment,” said Exxon spokeswoman Charlotte Huffaker. She said the Irving, Texas-based company was monitoring emission levels and was committed to complying with environmental laws.

The Baytown refinery is the second-largest in the U.S. Exxon’s disclosures highlighted the danger posed by flooding in a refinery-rich section of the Gulf Coast that stretches from Corpus Christi, Texas, to Louisiana.

The flooding has caused the shutdown of about 15 percent of the nation’s refining capacity, sending gasoline prices higher.

Gasoline futures rose 6 cents, or 4.1 percent, to $1.78 a gallon in trading Tuesday. Retail prices have gained more slowly – up 4 cents in the last week to $2.38 a gallon, according to auto club AAA.

Earlier Tuesday, Motiva Enterprises said that its refinery in Port Arthur, Texas – the biggest in the nation – had cut output to just 40 percent. Motiva, which is owned by Saudi Aramco, the state-owned oil company of Saudi Arabia, said it was dealing with restrictions in the flow of crude oil coming in and products like gasoline going out through pipelines and ports.

A company spokeswoman said there was some water in the plant and local roads were flooded.

The operator of a major pipeline carrying fuel to the East Coast announced it was running at a reduced rate too, compounding pressure on the nation’s energy system.

The Colonial Pipeline operator said Tuesday the reduction was due to limited supply from refiners around Houston and storm damage to its facilities in several southeast Texas locations. The company said it dispatched workers to the region.