US investigators say they “have yet to determine” why an 87-year-old driver allegedly ran a red light at an intersection in Nashville at the weekend, killing Australian broking leader Tim Wedlock and injuring three other pedestrians.

“All were in a crosswalk with the right of way when they were hit,” the most recent police statement says.

The driver has been named as Thomas Cahill of Bowling Green, Kentucky. He remains in hospital in a stable condition.

“Officers have not yet been able to speak with him, but hope to do so soon,” police said.

“In the 2013 Ford Fusion with Cahill were his 90-year-old wife, in the front seat, and her care-giver, in the back seat.

“The wife was transported to hospital with non-life-threatening injuries. The care-giver was uninjured. She told officers she was looking down at her phone when the collision occurred.”

Two of the three surviving pedestrians remain in hospital in a critical condition. The third has been discharged from hospital.