The motive remains unknown.
The attacker, a 39-year-old woman, was taken in custody and no motive for the assault was released.
The Islamic State claimed responsibility.
He suffered brain trauma.
Two girls are also in serious condition after Saturday's attack.
Police say a 27-year-old man injured six passengers, including a young child.
Police said they are investigating whether there was an Islamist motive to the attack.
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Police say they have arrested two suspects.
Authorities in Florida say they arrested two rowdy women on Wednesday after their rejected flash-for-beer money offers led