Somtawin Ngarm-naeramitdee, 44, suffered an epileptic fit while exiting an underground parking garage at the Old Siam shopping mall on Tree Petch Road near the Chalerm Krung intersection, police said.
He reportedly stopped breathing upon arrival at BMA General Hospital and was placed in intensive care, according to Jor Sor 100 FM radio station, which broadcasts city traffic reports.
Pol Lt Nattakorn Wuthisook, an investigator at the Phra Ratchawang police station, quoted Tidaporn Khamparn, Mr Somtawin's sister-in-law, saying that Mr Somtawin was about to stop the car to pay the parking attendant when he had the seizure. He hit the accelerator and the car zoomed across Tree Petch and rammed the Mae Thong Bai gold shop on the opposite side.
No other cars were passing at the time. Ms Thidaporn and Petchawan Sinparbruangchai, 37, daughter of the shop owner, sustained minor injuries.