A 69-year-old FedEx worker was found dead in subzero temperatures outside an Illinois delivery hub on Thursday –– and authorities are working to determine whether the dangerous weather played a role in the death.

William L. Murphy was found dead around 9:24 a.m. on Thursday at FedEx Freight in East Moline, Illinois, after collapsing outside the delivery hub more than a day before, Rock Island County Coroner Brian Gustafson tells PEOPLE.

“It was very frigidly cold,” Gustafson tells PEOPLE, noting that Murphy’s exact cause of death has not been determined. “Could [the weather] have caused him to go into cardiac arrest? Possibly.”

A delivery man works in New York City on Jan. 21.STAN HONDA/AFP/Getty

US-WEATHER-SNOW

On Tuesday, temperatures in Moline plummeted to -12 degrees, according toThe Weather Channel. By Thursday, temperatures reached as low as -27 degrees.

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The incident is the latest in a string of weather-related deaths as brutal cold from thepolar vortex grips the Midwest. At least 21 people have died as the temperatures have plummeted, according toThe Weather Channel.

A homeless man in New York City on Jan. 30.Drew Angerer/Getty

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Dozens of people across the country have been hospitalized for symptoms of hypothermia and frostbite sustained as a result of the bitter cold, theThe New York Timesreported.

Among the dead are an18-year-old University of Iowa studentfound outside a campus building; four men found frozen in Illinois, Wisconsin and Michigan and six Iowans who died in car crashes.

TheJames J. Versluistugboat breaks ice in Chicago on Jan. 30.Scott Olson/Getty

Polar Vortex Brings Extreme Cold Temperatures To Chicago

However, the warm weekend doesn’t mean the cold is through.

“It’s not the end of the movie yet,” Judah Cohen, a winter storm expert for Atmospheric Environmental Research, told theAssociated Press. “I think at a minimum, we’re looking at mid-February, possibly through mid-March.”

source: people.com