LUKE, Md. (AP) -- NewPage Corp. says it's investigating a chemical leak that sent four workers at its western Maryland paper mill to hospitals for evaluation.

Authorities told the Cumberland Times-News that the workers suffered respiratory distress from chlorine dioxide that leaked from a storage tank at the mill in Luke shortly before noon Wednesday ( http://bit.ly/vQivR3 ).

The company said in a statement late Wednesday afternoon that a section of state Route 135 was briefly closed and people in the community were advised to stay indoors for nearly an hour.

The Miamisburg, Ohio, company says the mill has returned to normal operations.

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Information from: Cumberland (Md.) Times-News, http://www.times-news.com/timesnew.html