Just one day after Kevin Long was released from prison, the 37-year-old registered sex offender is back behind bars for allegedly assaulting a teenage girl on a Modesto, California bus, CBS Sacramento reports.

According to witness Curtis Mitchell, who later came to the rescue of the teenaged victim, Long "made a verbal gesture to the young lady about ‘Have you had sex yet’ and the girl was freaked out."

Following the gesture, Long lunged out at the girl and grabbed her crotch area, Mitchell told CBS. Immediately, Mitchell and four friends, who are disabled and homeless, jumped up and pulled Long off of the screaming teen. The men reportedly held Long down for three blocks, until the bus driver pulled into the transit center where police officers were waiting.

In an interview with Fox 40, Long's family members said he never should have been released on parole, citing disturbing letters he sent from prison about his desire to have sex with children.

"I want to deeply apologize to the little girl and her family for what has happened. I did everything in my power to keep him from being out on the streets," a family member told Fox 40, requesting not to be identified.

According to the family, Long has been in and out of the system since he was 12 years old.

Passengers on the bus lauded the homeless men as heroes, but Mitchell says he's just a regular guy. "I have kids, grown up now, but I would hope someone would help my kids if they needed it,” he told CBS.

Long is back behind bars at Stanislaus County Jail, facing charges of lewd acts with a minor, sexual battery and parole violation, the New York Daily News reports. He is scheduled to appear in court on Tuesday.