Four youths in France have been placed under criminal investigation over a bus attack in which a woman was badly burned, a French prosecutor has said.
The Marseille attack was the worst incident so far this year
He says the fifth suspect, who is under 16, had been released but will be tried in court as an assisted witness.
The victim, 26-year-old Mama Galledou, suffered horrific burns during the weekend's arson attack in Marseille. She is being kept in an induced coma.
If she dies, the youths could face life imprisonment, correspondents say.
The five suspects were arrested on Tuesday. A criminal investigation is the first step before formal charges are brought.
France has seen a spate of bus attacks, a year after a wave of rioting engulfed its impoverished suburbs. In most cases the gangs let passengers off the bus before setting it ablaze.
But in the Marseille attack, a group of teenagers reportedly forced open the doors of the bus vehicle and threw an inflammable liquid inside before fleeing.
All the passengers managed to escape except Ms Galledou, a university student of Senegalese origin.
During three weeks of unrest last year, gangs of youths, many of them of North African origin, torched cars and clashed with police. More than 10,000 cars were set ablaze and 300 buildings firebombed.
Community leaders in run-down French suburbs have warned that the factors which played a key part in the riots - high unemployment, racial discrimination and alienation from mainstream society - remain unchanged.
The 2005 riots were sparked by the deaths of two teenagers in a suburb of Paris. There is dispute over whether they were chased by police before they were electrocuted while hiding in an electricity sub-station.