Three people were killed and four were seriously injured when a bridge in Mississippi targeted for demolition collapsed Wednesday afternoon, authorities said.

The bridge, located about 40 miles south of Jackson on State Route 149 over the Strong River in Simpson County, had been closed for nearly a month so crews could demolish it, the Mississippi Department of Transportation said in a news release. The bridge collapsed prematurely in what the department described as a "work site accident."

"Sadly, there were fatalities as a result of the accident, and we extend our deepest condolences to the families who have lost loved ones," the department said in its statement.

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Three killed, 4 critically injured in Mississippi bridge collapse

The bridge has been closed to traffic since Sept. 18 as part of a bridge replacement project and a contractor was in the process of demolishing it before the collapse, the department of transportation said.

Gov. Tate Reeves confirmed late Wednesday on social media that three workers were killed.

"We have confirmed multiple injuries and at least three fatalities from the accident. As the situation develops, authorities will provide more information while respecting the privacy of the bereaved," Reeves said in a statement shared on Facebook. "Please keep the families and coworkers of everyone involved in your prayers."

Terry Tutor, the Simpson County coroner, told the New York Times that seven men were using heavy machinery on the bridge to tear it down when it gave way and plummeted nearly 40 feet.

Reached Thursday by USA TODAY, Tutor confirmed that three of the men died and four were injured. He identified the men who were killed in the collapse as Kevin Malone, Charles Ingleharte, and Charles Badger.

Simpson County Sheriff Paul Mullins told WLBT-TV, an NBC affiliate station in Jackson, that the four people who were injured were in critical condition.

Mullins did not immediately return a message left Thursday morning by USA TODAY.

Federal government briefed on collapse; cause undetermined

U.S. Transportation Secretary Pete Buttigieg said on social media site X that he was briefed on the "premature collapse."

In his post, Buttigieg said the Federal Highway Administration was “engaging state officials concerning” the fatal accident.

"Our thoughts are with the workers who were injured and lost their lives, and with their families," Buttigieg said.

An inspector with the state's department of transportation was on site during the collapse and was unharmed, the department said.

It was unclear as of Thursday morning what had caused the collapse.

This story has been updated to add new information.

Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at [email protected]