Federal regulators are investigating after two workers became trapped Thursday inside a chocolate-filled tank at a Mars Wrigley factory in Pennsylvania.

Emergency crews were called Thursday afternoon to the factory in Elizabethtown, Pa., about 12 miles from the chocolate capital, Hershey. Brad Wolfe, communications supervisor for Lancaster County 911 Dispatch, told CNN that firefighters had to “cut a hole in the side of the tank to get them out.”

The workers, who have not been publicly identified, were taken to a hospital – one by helicopter, Nick Schoenberger, an assistant supervisor for the dispatch center, told CNN.

A spokesperson for Mars Wrigley, which makes M&M’s, Snickers and other candies, confirmed in a statement Friday to The Washington Post that the workers were taken off-site for evaluation. “We’re extremely grateful for the quick work of the first responders,” it read.

Their conditions were not immediately known.

Leni Fortson, a spokesperson for the Occupational Safety and Health Administration, which is investigating the incident, said the workers were performing maintenance work inside the vat when they got trapped.

It is still unclear how the workers got stuck in the tank and how much chocolate was in it at the time. PennLive reported that dispatchers believed the chocolate was about waist level. Dispatchers also believed that it was dry chocolate, according to NBC’s “Today.”

Fortson said the workers were employed by I.K. Stoltzfus Service Corp., a company that provides industrial painting, cleaning and tank repairs. When asked about the incident and the employees’ medical status, a woman who answered the phone Friday morning at I.K. Stoltzfus Service Corp. declined to comment and referred questions to Mars Wrigley. Mars Wrigley would not provide further information.

OSHA said that it has six months to complete its investigation and release its findings.

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