Simonsen, competing in the GTE Am class, was driving the #95 Aston Martin Vantage GTE when he lost control and spun at high speed. The car eventually skidded into a barrier at the Tertre Rouge corner.
The accident caused the safety car to come out and the race to be delayed by an hour while the barrier was repaired.
This was the 34-year-old’s seventh Le Mans race. Sharing his car this year were Kristian Poulsen and Christoffer Nygaard.
In a statement, Aston Martin racing director John Gaw said: “On behalf of all of us at Aston Martin, I would like to extend our deepest sympathies and condolences to the individuals and families whose friends or loved ones were involved in today's terrible tragedy.”
The automaker has four other cars competing this year and will continue its campaign, at the specific request of Simonsen’s family. A further statement will be released once precise circumstances of the accident have been determined.