New York (CNN) -- The New York City Police Department was searching Wednesday for a man who allegedly punched a 33-year-old woman in the back of the head in Brooklyn, in what could be the latest in a spate of "knockout" assaults.
The incident occurred just before 3 p.m. on Saturday, but police released a sketch of the suspect Tuesday.
The unidentified woman and her 7-year-old daughter were walking in the Midwood section of Brooklyn when the attacker approached her and punched her in the back of the head, knocking her down, then fled on foot, according to the NYPD.
The woman sustained minor injuries to her knees and hands when she fell, police said.
The suspect is described as about 5 feet 7 inches to 5 feet 9 inches tall, with short braids, and was wearing a black wool cap, green jacket, and dark-colored jeans, police said.
This latest attack follows a series of assaults known as the "knockout game," where teens try to knock random strangers unconscious with a single blow.
At least nine suspected "knockout" attacks have been reported since October in New York, but police have said they see no evidence of a trend.
A NYPD spokeswoman told CNN on Wednesday that police "investigate each assault individually" and that the latest attack was still under investigation.
In November, a 23-year-old man was walking in the Bronx one afternoon when he was punched and knocked to the ground by men who continued to punch him after he was down.
Authorities have reported similar incidents in New York, New Jersey, Connecticut, Illinois, Missouri and Washington.
In New Haven, Connecticut, police said there were seven reported incidents possibly connected to "knockout" assaults, but it was unclear if they were carried out by the same person. There were no major injuries in the attacks, which occurred in the same three- to four-block area on November 17-18.
The assaults stopped after police questioned a suspect, though no arrest was made. "We have no reason to believe this is a hate crime," said Officer David Hartman, a New Haven police spokesman. Some previous assaults in the region have targeted Jewish people.
Hartman said police believe the attacks were copycat crimes spurred by media attention.
Youth violence expert Chuck Williams blamed the media and parents for what he called extreme aggression by America's youths. Negative attention, he said, is often rewarded.
"That's America. America loves violence, and so do our kids," he said. "We market violence to our children and we wonder why they're violent. It's because we are."
Williams, a professor of psychology and education at Drexel University in Philadelphia, said some young people are desperate for attention. He called it the "Miley Cyrus effect," where teens will do anything, no matter how unconscionable, to get noticed.
"These kids know the consequences," he said. "They want to get arrested. They want to get caught, because they want that notoriety. They know they won't go away forever because they're kids. It's a win-win all around for them."
CNN's Morgan Winsor contributed to this report