'Zoey 101' Star Matthew Underwood Saves Baby From Heroin-Fueled Car Crash

Former "Zoey 101" star Matthew Underwood rescued a 4-month-old baby after the infant's parents passed out on drugs and crashed their car ... TMZ has learned.

Law enforcement sources tell us Matthew was one of the first people on the scene of a car wreck last Thursday in Port St. Lucie, FL ... where a female driver cut across 6 lanes of traffic on a busy street and crashed into a tree.

We're told she passed out at the wheel with a syringe full of heroin in her arm, with her baby daddy passed out in the back seat. Their baby was in an unsecured car seat next to the father.

According to the police report ... Matt saw the parents passed out, removed the infant -- who was not injured -- and had his brother call 911.

Matt also shot video of the scene before cops arrived. The mother later told cops she'd just bought heroin to try for the first time. The dad had a pill bottle full of Alprazolam (generic Xanax), a smoking pipe and a 2nd syringe laying next to him.

Matt tells us he decided to record the scene once he saw the parents passed out. He wanted to document the scene before he intervened in case things went south. He says he couldn't have just driven by without helping.

Both parents were booked for child neglect and drug possession. The baby was turned over to a family member.