The NYPD says synthetic marijuana is a big health problem in the city, across the state and across the country, and they are trying to get a handle on it. NY1's Dean Meminger filed the following report.

Police are sounding the alarm about smoking synthetic marijuana, also known as K2 or spice.

"Many of them under the influence of this drug, totally crazy, superhuman strength, impervious to pain," said Police Commissioner William Bratton.

Police say an increasing number of people are smoking synthetic marijuana, especially homeless people in the Bronx, central Brooklyn and upper Manhattan, because it's so cheap. A packet of the artificial pot goes for $2 to $5. But be careful what you buy.  

"This is a great unknown chemical," said Robert Messner of the NYPD's civil enforcement unit. "We don't know what these chemicals are. We don't know who's producing them. We don't know where they're being produced."

"Pretty much what they're selling is a tea bag called synthetic marijuana because it has the consistency of marijuana, that it looks like marijuana, but it's laced with chemicals," Bratton said.

And it can lead to extreme behavior, like one man running naked through the streets and yelling in front of an NYPD school safety van.

The police commissioner described another case in the Bronx.

"As the personnel were attempting to saw a hole through the door with an electric saw, this individual was so out of it, he literally grabbed hold of this electric saw with both hands and was totally impervious to the pain that was being inflicted on him, and it took quite a few efforts on the part of our officers to ultimately subdue him," Bratton said.

The NYPD says when it responds to calls of people smoking it, they often have to rush them to the hospital, not the precinct.

"From April 1 to June 30 of this year, there were over 1,900 admissions to hospital emergency rooms throughout New York State for individuals that took this substance," said NYPD Chief of Patrol Carlos Gomez.

It the last two months, the NYPD says it has taken more than 10,000 packs of synthetic weed of the streets. The police are now teaming up with other agencies in targeting stores and smoke shops that are selling it.