Police in New York City are looking for a suspected robber who violently targeted an 85-year-old man on a Bronx street over the weekend for $7, authorities said.

A woman approached the man from behind as he was walking on 170th Street and pushed him to the ground Saturday morning, police said. 

Surveillance video appeared to capture her on top of him and emptying his pockets. She fled with $7, police said. 

The man was taken to a hospital and was listed in critical condition. The robbery comes as the city continues to see an uptick in violent crime

On Monday Mayor Bill de Blasio announced the New York Police Department was upping patrols in subway stations after a series of incidents where straphangers were shoved onto subway tracks. 

“I’m real concerned, and we gotta make sure that New Yorkers have confidence that they can go and use the subway and know help will be there for them," the Democratic mayor said during a Monday morning press conference. "So, NYPD is going to be increasing its presence in the subways. That will be very visible.”

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On Sunday night, a 20-year-old woman was fatally shot during a Sweet 16 party in Brooklyn, the New York Post reported. Six others, including a 14-year-old girl and boy, 15, were shot at the same location. Authorities said the incident appeared to be a targeted attack.  

Citywide, 13 people were shot Sunday. 

Fox News' Stephanie Pagones contributed to this report.