HACKENSACK, N.J. - After several arrests, a 22-year-old man vowed last August he was going to straighten out. A month later, he died of a heroin overdose in his grandfather's Paramus home, Bergen County's 12th fatal overdose in three months.

On Feb. 8, a 21-year-old volunteer firefighter from Glen Rock died in his parents' house 24 hours after leaving left rehab. In March, two months after his arrest for burglary, a 20-year-old died of a heroin overdose in his father's Montvale home.

In two years, heroin has claimed at least 50 lives in Bergen County and has its grasp on hundreds more. Once they were talented athletes or promising students. Now they drive into Paterson several times a week to buy heroin.

Most got hooked through prescription painkillers such as Oxycontin and Opana. Heroin, at $5 per bag, is far cheaper, potent, and widely available.

"An absolute epidemic," said Bergen County Prosecutor John L. Molinelli, who has led a task force to crack down on North Jersey's heroin trade. "These kids have no idea what they're getting into."

Heroin use is on the rise, particularly among suburban youth. Between 2007 and 2011, the number of users nationwide went from 373,000 to 620,000, according to federal data, and heroin-dependent young adults more than doubled to 109,000 between 2009 and 2011.

Heroin has been tied to gang activity - most of it attributed by prosecutors to the Bloods, a national gang with offshoots in Newark and Camden as well as Paterson.