Two elderly women were killed when their friend drove into the wall of a church they had just attended, an inquest heard.
Jane Hogan, 92, and Johanna Street, 82, both died from multiple injuries after 72-year-old Joyce Cunningham rammed her Ford Focus into the wall of St Catherine's Church, Littlehampton, on April 22.
An inquest at Worthing heard Mrs Cunningham might have been overcome by "Sudden Acceleration Syndrome" or possibly suffered from a seizure.
The chorister, from Littlehampton, survived but was seriously injured.
The inquest heard the S-registered car was seen reversing at speed out of the church car park before stopping in Beech Road.
There was then a short pause before it sped forward 30 metres, striking the east wall of the church.
In a statement made to police after the crash, Mrs Cunningham said: "I started it with the ignition key and all hell broke loose.
"The car shot backwards on to the road and then it shot forward again and hit the church wall. It seemed to me that the car was going at some speed.
"I can't remember how this occurred. I simply don't know what happened."
PC Graham Welsh, of the Sussex Police crash investigation unit, said the accident had been caused by driver error.
He said the incident showed aspects of Sudden Acceleration Syndrome, which usually afflicts elderly drivers in unfamiliar cars.
Mrs Cunningham had bought the manual-geared car the month before the accident.
PC Welsh said it was unlikely she had suffered a seizure or fit as Mrs Cunningham had carried out a conscious manoeuvre in the road.
He said: "She had managed to operate the controls, although I'm sure she was in a blind panic as she was doing so.
"Had she stalled, it would have been a different matter. It is very sad that these two ladies met their end in such an unfortunate way."
West Sussex Coroner Roger Stone recorded verdicts of accidental death on the two friends, who both lived at Armada Way, Littlehampton.
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