NEW YORK - New Yorkers are no stranger to weird sights on the subway, but some say bringing motorized bikes into the system crosses the line.

New video posted to the Twitter account @NYC911 shows three people rolling their motorized bikes onto crowded subway cars.

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It's unclear when the incident happened, but it took place on an train at the Rockefeller Center station.

"Very dangerous. That's not good. I think that maybe the transit police should be down here monitoring it more," said one subway rider.

"I think it's not okay, if you have something motorized go on the street and don't bother us on the subway," said another subway rider.

"It's unsafe for sure, but you just have to be careful I guess because there all sorts of people going in and out of subways," noted a third rider.

The NYPD says it's aware of the video and it's investigating.

So far, no arrests have been made.

Anyone with information on the case should contact the Crime Stoppers hotline at 1-800-577-8477, or text CRIMES and then enter TIP577, or visit www.nypdcrimestoppers.com.