ST. LOUIS – A bizarre and frightening incident on a very busy stretch of a highway left one person dead.

Police told us a woman was driving on Highway 40 in the city of St. Louis, when a piece of metal smashed through her windshield, killing her.

There are still unanswered questions Thursday morning, including where the metal came from, as well as the name and age of the woman who was killed. St. Louis Police told us the woman was driving a 2012 Mercedes E350 westbound on Highway 40 Tuesday afternoon just after 12:30 p.m. They shared that she was near South Vandeventer when a piece of metal crashed through her driver’s side windshield.

We’re told the woman hit then the north concrete wall several times before coming to rest on the right shoulder of the highway just before South Vandeventer. She was taken to a hospital, where she was pronounced dead.

Authorities explained at this point it’s unclear if the piece of metal came off of a vehicle or was debris from the roadway. The accident reconstruction team from the St. Louis Police Department has taken over the investigation.

City officials said in a statement, “The city of St. Louis Streets Department works every day to ensure trash and debris are cleared from our roadways and ensure safe passage for drivers, cyclists, pedestrians, and public transit users alike.”

City officials also said that if you see debris blocking a roadway, you are asked to contact the city’s Citizen’s Service Bureau either by phone, online, or the Bureau’s Twitter.

That phone number is 314-622-4800.

The Missouri Department of Transportation declined to comment for our story.