The shooting sent about 100 people fleeing in a "very chaotic scene," Acting Police Chief Mark Simmons said.
Police believe at least three or four people were in possession of handguns and at least 40 rounds were fired, said Capt. Frank Umbrino during a Saturday press conference.
Two 19-year-olds were pronounced dead at the scene, Umbrino said. Neither of the teens were residents of the home where the shooting occurred and neither were likely intended targets, Umbrino said.
No suspects were in custody, and no motive was immediately known, Simmons said.
"A number of our young people -- babies -- that came to just hang out a little while ... left running for their lives (Saturday). And that's just something that we cannot have happen," Warren told reporters.
Warren said she spoke to the party's host, who said she "invited a couple friends over, who invited a couple friends over who invited a couple friends over."
"And it just got out of control. She's just traumatized," Warren said.
The 14 wounded range in age from 17 to 23 years old, and were taken to two hospitals with what are believed to be non-life-threatening injuries, police said.
Police responded to calls of gunshots around 12:25 a.m. and were met with 100 to 200 people attempting to flee on foot and in vehicles, Umbrino said.
The shooting occurred at a house party where a limited number of people were invited, but people from two nearby parties "infiltrated" the house and at some point, an altercation ensued and escalated, Umbrino added.
Police were not aware of the party beforehand, and had not received any calls for disturbance, Simmons said.
"For our community, (which) is right now going through so much, to have to be dealt with this tragedy (Saturday's shooting), needlessly -- for people who decide to act in a violent manner -- is unfortunate and shameful," Simmons said early Saturday.
"We're going to do everything that we can as a department to bring those people involved to justice," he said.
Counselors -- including those from the city's schools -- are going to be available at five Rochester recreation centers Saturday afternoon to support the community in the shooting's wake, Warren said.
Warren said city resident should "stay calm and allow these folks (police) to do what they need to do to bring" whoever was involved in Saturday's shooting "to justice."
She asked that "everyone to obey the (11 p.m.) curfew ... and not have these mass gatherings."
"Please keep our city in your prayers. Keep the families in your prayers, and of course all these neighbors that live here that had to experience this tragic situation who are all hurting and suffering and crying right now," she said.
CNN's Christina Maxouris, Alec Snyder and Alta Spells contributed to this report.