The group punched and scratched the woman's head, then one of them bit her finger, police said.
The attackers beat the four victims and stole cash and valuables early Sunday, police said.
Two women were robbed by a teen girl in separate incidents just minutes apart, police said.
Both gunpoint muggings took place this month in the 71st and 77th precincts.
Police arrested three people for the attack on a 15-year-old at Battery Place and Greenwich Street.
A pair of men threatened a President Street resident and made off with $400, officials said.
A group of four teens robbed four people uptown, including two men in their 60s, police said.
Two 15-year-old girls threatened to stab people in Fort Tryon Park if they didn't hand over valuables.
A mugger shot his victim in the leg after the man withheld $260, police said.
Two men tried to rob a passenger on a Q train Tuesday, police said.
Anthony Coward, 28, was charged with robbery in the attacks, police said.
A man was robbed inside Harlem's Wolf Style Clothing on March 18, police said.
The kids, aged 12 - 16, were arrested in connection to a Central Park mugging spree, police said.
Boys as young as 12 were being questioned about the Central Park robberies Monday morning, sources said.
A 43-year-old man was shot to death trying to fend off robbers early Sunday morning, police said.
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