Claysburg, PA – Several workers at the Sheetz Distribution Center in Claysburg were hospitalized Sunday night after officials detected elevated carbon monoxide levels in a freezer and cooler area.

Federal officials are set to investigate the incident, which followed employees’ reports that something might be wrong at the facility. Workers tested the air quality and found elevated levels, prompting a maintenance team to ventilate the area overnight, public relations manager Nicholas Ruffner said Monday.

Ruffner said employees who had worked in the affected area were encouraged to seek medical treatment. About nine went to hospitals, and all had been released by Monday afternoon, he said.

Ruffner said he is not sure whether the affected employees reported feeling ill before the situation was investigated.

“I don’t have the information in front of me to know exactly what they were reporting,” he said.

Carbon monoxide — a colorless, odorless gas — can cause weakness and dizziness, with extreme exposure capable of causing death.

The incident comes amid a two-month period in which an outside contractor has been repairing floor seams in the distribution center’s freezer and cooler areas, Ruffner said in a written statement.

The Claysburg facility, one of two controlled by Sheetz, handles product distribution for the northern half of the company’s Mid-Atlantic presence.

On Monday, an official with the federal Occupational Safety and Health Administration said the agency was aware of the incident and would look into it.

“We will be investigating that incident. I can’t giveany further details,” said David Rhodes, agency assistant area director.

Air quality in the affected area had returned to normal levels by Monday afternoon, Ruffner said. He said the company consulted with the Pennsylvania Department of Agriculture and determined that, because all the food stored in the area was in sealed packaging, it could be sold without concern.