Former Tata Sons chairman Cyrus Mistry and a co-passenger killed in the car crash on Sunday were not wearing seat belts as per the preliminary probe, a police officer said, adding over-speeding and the "error of judgement" by the driver caused the accident.

Prima facie, the luxury car was speeding. It covered 20 km of distance in just 9 minutes after crossing the Charoti check post in the Palghar district, 120 km away from Mumbai. The car hit a road divider on the bridge on the Surya river, killing Mistry (54) and Jahangir Pandole on the spot.

Mistry was returning to Mumbai from Ahmedabad when the tragedy struck at 2:30 PM.

The car was driven by Mumbai-based gynaecologist Anahita Pandole (55).

She and her husband were seriously injured in the accident.

"As per the preliminary investigation, overspeeding and the error of judgement caused the car accident. Both the deceased were not wearing seat belts," the officer said on Sunday night.

"While analysing the footages captured by CCTV cameras at the Charoti check post, Palghar Police found that the car had crossed the check post around 2.21 pm and the accident occurred 20 km ahead (in the direction of Mumbai)," he said.

This shows the Mercedes car covered 20 km of distance (from the cheek post) in just 9 minutes, the officer said, adding that the accident occurred at 2.30 pm on the bridge on the Surya river.

Mistry and Jahangir Pandole were in the back seats. Darius was in the front seat with Anahita, who was at the wheel, police had said.

An eye-witness had said that a woman was driving the car and tried to overtake another vehicle from the left side, but lost control and crashed into the road divider.

The bodies of Mistry and Jahangir Pandole have been sent to state-run J J Hospital in Mumbai for postmortem, the officer said.

Anahita Pandole and her husband Darius Pandole (60) were seriously injured in the accident. They are being shifted to a Mumbai hospital by road from Vapi in Gujarat on Sunday late night, the officer added.