The shooting happened around 12:30 a.m.
The victims include five men and four women. Two of the men are in critical condition.
A fifth woman was also injured in the chaos, but she was not hurt by gunfire, police say.
Police are looking for a dark-colored SUV connected to the incident. There have been no arrests and no word on the identity of any suspect or suspects.
A news conference with the mayor and police director is expected at 4 p.m. Saturday.
A city councilman was outraged over the violence.
"Every time we get a break in the weather, a few in this city want to engage in gunplay. And I know that the police are working hard, they're working so hard to address this crime wave, but they need more resources," said Councilman Jerell Blakeley.
"I call on the state troopers, I call on the National Guard. We need something in this city," Blakeley continued.
This is the second shooting in Trenton in less than a year that has injured multiple people.
Nearly 30 people were hurt in a shooting at the Art All Night Festival last June.