Shooting victims Charlene Holmes, middle, and Thanialee Cotto are seen in images from Charlene’s obituary page and Facebook, respectively. The drive-by took place on Willow Street in the Wellington-Harrington neighborhood.

Two girls, 16 and 17, were shot just before 8:02 p.m. Sunday on Willow Street, one fatally, police said.

The girls were shot while sitting on the porch of a Willow Street home in the Wellington-Harrington neighborhood. They were taken to a hospital, where one died, police said. The second victim remained in critical condition throughout the night.

While Middlesex District Attorney Gerry Leone and Cambridge Police Commissioner Robert Haas gave information resulting from the shootings and 911 call at a careful pace Sunday, people on Twitter and other social media were reporting almost immediately afterward that Charlene Holmes and Thanialee Cotto were the girls shot. A family member confirmed late Sunday that it was Charlene, 16, who had been killed.

“I just lost my daughter. She was a beautiful, loving, wonderful person. She was a people person. She loved life,” Charlene’s mother, also named Charlene Holmes, told The Boston Globe.

Thanialee is reported as being a senior scheduled to take part in commencement ceremonies Thursday and then attend Newbury College in Brookline. Charlene was a sophomore.

“Whoever had the audacity to pull that trigger should be dead right now instead of Charlene,” said one girl who identified herself as a classmate at Cambridge Rindge & Latin School. “This summer, I’m either in my house — or not in Cambridge.”

Further Twitter reports said police were looking for a black sport utility vehicle involved in the incident, but The Cambridge Chronicle was told by a witness it was a black sedan; a police officer confirmed to Cambridge Day that the vehicle in question was a black Nissan sedan with tinted windows. Another Twitter report wondered if an arrest had been made, having seen a man who had been on Willow Street since before the shooting put into the back of a police cruiser, but police officers and officials said there were no arrests Sunday night.

Crime in Cambridge is at a historic low, police have reported recently, with the 3,567 serious crimes recorded in the city last year being the lowest reported to the FBI since such records began in 1963. There were five homicides last year. Haas, who was at the crime scene at least through midnight, said he could not immediately remember a crime similar to the Sunday shootings. “It’s been a long, long while,” Haas said.

“I have grown up in Cambridge for 17 years and know it be a safe and welcoming city. Never let the actions of a few idiots scare you,” said Samuel M. Gebru, president and chairman of the Ethiopian Global Initiative and a 2009 graduate of CRLS.

Mourning was widespread Sunday — including the creation of the Twitter hashtag #RIPChay so people could share their thoughts — as Cambridge Police and the Massachusetts State Police assigned to the Middlesex District Attorney’s Office stayed on Willow Street overnight, yellow crime scene tape cordoning off the neat homes southeast of Inman Square by the King Open School and Donnelly Field. City councillor Tim Toomey was also at the scene Sunday. He called the crime “horrible.”

“The Holmes family has all of Cambridge with them tonight,” said Beena Sarwar, a Pakistani journalist and artist living in the city. “Too much violence and hatred in the world. Too many weapons.”

A witness told the Chronicle he’d heard the shooting was “calculated.” Another told the Globe it was “retaliation.” Witnesses interviewed by WCVB, however, said a man getting his hair braided by Thanialee was the intended target and that Charlene Holmes was only walking past with her sister — and a call to Charlene’s home Monday afternoon found confirmation for that, along with an assertion “Charlene was not a part of that gang out there.”

The same person reached at Charlene’s home said a NECN report that the 16-year-old was pregnant had been corrected and retracted. “She was not pregnant,” the person said.

Cambridge rapper Milly Blanco, or Millyz, tweeted his sorrow for the crime: “RIP to the young girl who lost her life today in Cambridge to senseless violence. My condolences go out to the Holmes family.” Another Cambridge rapper, Jahmel McClamy, also known as Melz,was inspired to write a song called “The Innocent” and dedicate it to Charlene, while storyteller and poet Owen Grey composed a “Willow Street Elegy.”

Update: A spokeswoman in the District Attorney’s Office said Monday morning that Thanialee remained in critical condition. The hashtag #PrayForThania is being used by people expressing support for her, and a candlelight vigil for the girls was planned for 7 p.m. on Willow Street, to be moved to the nearby school cafeteria in case of rain, said Dan Riviello, a police spokesman.

This post was updated June 9, 2012, with a photo of Charlene Holmes from the Rogers Funeral Home obituary page.