Officers said that about 9:40 p.m. Friday, two men on a bicycle - one pedaling, the other perched on the handlebars - confronted a 24-year-old man in the street and shot him in the face. He was in critical condition late Saturday at the Hospital of the University of Pennsylvania.
Another bullet hit Tynirah, whose hair was being braided by an older girl. The bullet passed through the child's chest and wounded the older girl in the arm as she struggled to pull Tynirah away from the gunfire.
"She was everything to us," Renee Bradford, a friend of Tynirah's mother, told NBC10. "She didn't deserve this. She was simply trying to get her hair done.
"For her to get shot in the chest? She's a baby. No baby deserves to die like that."
A 28-year-old woman and a 21-year-old man, both bystanders, also were hit.
The bicyclist, later identified as Woods, and his passenger fled, but police found them nearby, still on the bike, before the passenger again ran off. He was seen tossing a gun, which police recovered.
Police said they had identified the second man and a search was under way.
Woods was sentenced to prison for 11 to 23 months in December 2011 after pleading guilty to carrying a firearm without a license, court records show.
Two previous firearms charges, dating to 2008, were withdrawn by prosecutors.
News of the shooting prompted student members of the human-rights organization Amnesty International USA, who had been meeting in Philadelphia, to organize an impromptu demonstration against gun violence.
About 100 activists marched to LOVE Park from Drexel University, where they were in training for an antigun violence campaign, chanting "Remember Tynirah" as they walked.
"Youth and children have the right to feel safe in their communities and shouldn't have to worry about gun violence," said Rachel O'Leary, chief activism officer for Amnesty International USA.
In Grays Ferry, neighbors made a small memorial to Tynirah, piling up teddy bears and candles at the scene.
"There's nothing much you can say about this tragedy," Mike Collins told NBC10. "That was my little cousin. It hurts."
Inquirer staff writers Walter F. Naedele and Harold Brubaker contributed to this article.