Two contractors working at Illinois’s Granite City Works steel plant were hospitalized Thursday and treated for carbon monoxide exposure, U.S. Steel said.

The incident occurred just hours after President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE toured the facility and gave remarks to steelworkers, according to St. Louis’s KMOV.

Ten other workers were reportedly given health evaluations on-site but were not taken to the hospital.

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Trump spoke to steelworkers in Granite City on Thursday, and has taken credit for the facility’s reopening after the president imposed tariffs on imported steel from some countries earlier this year.

U.S. Steel earlier this year reopened one of the plant’s blast furnaces after Trump announced 25 percent tariffs on some steel and aluminum imports.

KMOV reported that the hospitalized contractors were working on the facility’s blast furnace “A,” which is currently offline. The company hopes to reopen blast furnace A by October.

U.S. Steel said they are investigating Thursday’s incident, according to KMOV.