A security guard who deliberately rammed his car into a crowded pizzeria in France told investigators he was a suicidal habitual drug user and had consumed "a large quantity" of painkillers the day before the act that killed a girl, a prosecutor said.
Eric de Valroger, a prosecutor in the town of Meaux east of Paris, described the suspect as "incoherent" and said his interrogation was proving "very complicated" and confusing.
The prosecutor reiterated that he had "totally" ruled out terrorism as a motive for the driver's as-yet unexplained actions.
Mr de Valroger said it remains unclear if the 32-year-old man intended to kill when he rammed his BMW into the restaurant that had about 30 people inside and on a terrace outside.
The prosecutor said the security guard simply described the restaurant in the village of Sept-Sorts as an easy, unprotected target.
The suspect - who faces aggravated murder and other charges - told investigators he had no beef with the pizzeria's owner and that he did not know his victims, Mr de Valroger said.
The driver showed signs of paranoia, "saying repeatedly that he felt as though as he was being followed, that the police were investigating him," he said.
"He describes himself as being out of control at the time of the incident. He is very confused about the motives. He says that if he commits an act that sends him to prison, he will be safe," the prosecutor said.
The driver was quickly arrested in what was the latest of several attacks in France and elsewhere using a vehicle as a weapon. Mr de Valroger says the investigation promises to be long.
The prosecutor said the man had a 2010 conviction for drunken driving and told investigators he had abused drugs since he was nine years old.
The driver also told investigators that he consumed large doses of mild painkillers on Sunday but gave conflicting explanations for why.
"He said initially that he aimed to kill himself, knowing full well that these medicines couldn't end his life," the prosecutor said. "He later eventually said that it was to help him sleep."
Tests showed that the driver had consumed drugs but not alcohol before he accelerated into the restaurant, travelling so fast that the car lodged inside.
He tried reversing out, but several restaurant patrons blocked his path and tried to pull him from the BMW before police arrived, the prosecutor said.
Of the five people most seriously injured, a 44-year-old woman remains in danger, the prosecutor said. The others, including a three-year-old boy who was flown by helicopter to a Paris children's hospital, are out of immediate danger, he added.
Seven other people with lesser injuries remain in hospital, he said.
The three-year-old boy's adolescent sister was the person killed. The prosecutor said the children's father was also injured.