NEW YORK (CBSNewYork)Synthetic marijuana, also known as “K2” and “Spice,” is a synthetic drug gaining popularity among the homeless in NYC because of its low-cost and availability.

Bodegas illegally sell synthetic marijuana for $5 a packet, according to police.

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The NYPD admits use of the drug is a crisis, and while many users enter a catatonic state, a few can turn violent.

“It’s laced with chemicals and as fast as we are able to identify the chemicals and get that particular chemical — make it against the law — they change the makeup of it,” Bratton said.

In a disturbing video obtained by CBS2, a naked homeless man, said to be under the influence of synthetic marijuana, is seen blocking a Brooklyn school safety vehicle. The man is howling and irrational.

While it’s not a new drug, it is being described by many as the new heroin or crack.

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Here are 5 facts you may not know about K2:

Fact 1: Synthetic marijuana refers to the many herbal mixtures inaccurately marketed as safe and legal, that produce marijuana-like effects. It’s often labeled “not for human consumption” and is sold as incense, but looks more like potpourri, according to the New York City Dept. of Health.

Fact 2: Many people use K2 because they wrongly believe it is natural and safe. It is also popular because it is not detected in most standard drug screens.

Fact 3: The drug is mainly smoked, like marijuana, but can be added to hot water for drinking.

Fact 4: Synthetic marijuana is illegal to sell in NYC but is legal to smoke.

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Fact 5: In NYC, men account for 90% of K2-related emergency department visits, says the DOH. Side effects include paranoia, lethargy and loss of consciousness. In rare instances, use of synthetic marijuana has been linked to death.