NEW YORK -- The NYPD is investigating. At least four more happened over the weekend in Manhattan.
Police believe they may be tied to dozens of other crimes, CBS2's Natalie Duddridge reported Monday.
Cellphone video shows two men in hoodies on a motorcycle pulling up to a man Saturday evening at the corner of Nagle Avenue and Arden Street.
Police said one suspect flashed a gun then assaulted and robbed the 28-year-old man who tried to run. Officers said one shot was fired, but no one was hit.
"He started screaming, like, 'Help,' and stuff like that," said a man who was working nearby. "They tried to take his chain and flee on the bike. The guys tried to jump him."
Video shows a bystander ran to his aid, but appeared to get hit in the head. The suspects took off and the good Samaritan tried to chase after them.
"That's a good thing that the people of the neighborhood could look out for one another," said one Inwood resident.
Police believe the pair of suspects robbed three other men - ages 69, 42 and 32 - of jewelry in the same neighborhood in a span of just 30 minutes. Police said the victims' injuries were minor. They're still looking for suspects and trying to determine if the crimes are connected.
"There's roughly 30 to 35 robberies that we believe these two individuals on this illegal bike are committing these robberies," said Deputy Chief John Chell.
Police are also investigating if they're connected to. Surveillance video shows two suspects rode up to two women outside the Guggenheim Museum on East 89th Street and tried to snatch the one woman's necklace. Her friend jumped into action and fought the men off and the suspects fled.
There was also. Police said a 64-year-old man was walking down West 23rd Street when a passenger on a dirt bike got off, grabbed the his watch and pushed him to the ground.
The NYPD's community response team was out in force Monday to put the community at ease.
"We engaged two illegal bikes on the sidewalk right behind me and one of those bikes had an illegal firearm on them," said Chell. "Is it the bikes involved in a robbery? No. Does it show our presence up here? Yes."
Police are hoping someone recognizes the pair seen riding around on a black bike.
Anyone with information is asked to call the NYPD's Crime Stoppers hotline at 1-800-577-TIPS (8477), or for Spanish, 1-888-57-PISTA (74782). You can also submit a tip via their website or via DM on Twitter, @NYPDTips. All calls are kept confidential.
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