(NewsNation) — Thieves are getting their hands on scrap metal as a way to make fast cash, a trend that is growing across the U.S.

These thieves are working to get their hands on everything from catalytic converters from vehicles to copper wires, statues and other metals for quick resale.

People wanting to make money off pieces of scrap metal are bringing their stolen goods to a scrap center, but it is hard to tell what metals will sell well and what won’t.

At Active Recycling in Los Angeles, workers typically turn away anything that was obviously stolen, but workers say that it continues to be a lucrative practice at other shops.

“We don’t question it, but we look at it, and we can pretty much tell, with the experience we have, we could tell pretty much what it’s from, and if it’s something like from like a catalytic converter, we don’t buy it,” Errol Segal, the owner of Active Recycling told NewsNation.

On Tuesday, thieves left LA’s landmark Sixth Street Bridge in the dark after cutting and stealing much of the copper wiring from the bridge’s lights, one of the hottest items on the market right now.

Currently, copper and brass are the most popular scrap metals. According to current market prices, copper is worth about $4.50 a pound, up 20% over the past year and 70% over the past five years. Brass is worth $2.41 a pound, up about 20% in the past year.

In Los Angeles County, over 300 fire hydrants have been stolen off city streets since the start of last year, a device that uses brass and copper parts.

In a tragic case from May, General Hospital actor Johnny Wactor was shot and killed during an attempted catalytic converter theft in downtown Los Angeles.