A teenager was killed in an overnight car accident on the Gulf Freeway. Authorities said four teens were in a car that was speeding down Interstate 45 South near Monroe.

The driver tried exiting the freeway and lost control on the feeder road.

The car then struck two utility poles.

Cynthia Castillo, 15, who apparently was not wearing a seatbelt, was thrown from the vehicle. She was taken to Ben Taub with serious head injuries and later died. She was just one month shy of her 16th birthday.

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Cynthia Castillo would have turned 16 next month. She was killed in an overnight accident on I-45.

The driver of the car was her 18-year-old brother the dead girl's father told 11 News. Police said the brother faces possible charges related to the accident. The other two passengers in the car were Castillo's boyfriend and her brother's girlfriend. Castillo was the only one not wearing a seatbelt at the time of the accident, said police. All four were on their way home from a group outing when the accident happened.

The other teens in the car suffered minor injuries and are expected to recover.