A Hofstra University junior sharing an off-campus house with her twin sister and several other students was shot and killed during an early morning break-in Friday that also left the armed intruder dead, police said.
Rebello's twin, Jessica, was also in the Uniondale house at the time of the 2:30 a.m. shooting, but she was not harmed, police said.
The shooting at the rental house, about a block south of the college, rocked the campus community just two days before commencement ceremonies.
Authorities said police were involved in the shooting, but it wasn't immediately clear who fired the fatal shots or how many rounds were fired. The gunman was not identified.
"We are going to get to the bottom of exactly what happened," Nassau police Chief Rick Capece said. "We have to do this the right way."
Capece said investigators were waiting for the results of a forensic analysis at the crime scene.
Police said the gunman barged into the two-story house on California Avenue at 2:20 a.m. and demanded money from the four Hofstra students inside -- the Rebello sisters, a man from Brooklyn and a woman from Connecticut.
The gunman let that unidentified woman leave the house to go to an ATM to get cash. She instead called 911, police said.
Shortly after officers responded to the robbery-in-progress call, "there was a police-involved shooting . . . in the home," a police spokesman said.
Police said a gun was found inside the house. No further details were available.
An emergency scanner transmission between police about 2:30 a.m. said that a woman had called 911 from a bank to report a home invasion -- and said she had gone to the ATM to withdraw cash while a man was holding a female friend at gunpoint.
About that time, Victoria Dehel, who lives four houses away, said she heard what sounded like fighting. At first she ignored it, figuring it was rowdy students returning from a bar.
Suddenly, she said, she heard a woman's shrieks, followed seconds later by loud bangs.
"It didn't sound good at all," Dehel told The Associated Press. "I turned to my boyfriend and I said, 'I think someone just got murdered.' It was awful."
The shooting rattled students, administrators and faculty at Hofstra, who released a statement Friday morning -- the last day of classes.
"While our hearts are laden with grief, this weekend's commencement ceremonies will go on as scheduled," Hofstra President Stuart Rabinowitz said. "The accomplishments of our graduates must be recognized, and together our community will heal and find the strength to move forward."
He led a moment of silence Friday afternoon during the convocation for about 200 Hofstra honor students who will graduate Sunday.
"All of us will always look back at graduation in 2013 with a sense of sadness," Rabinowitz said afterward, choking up.
Andrea Rebello and her sister were 2010 graduates of Sleepy Hollow High School, according to Principal Carol Conklin-Spillane.
The house where the shooting occurred is across the street from California Avenue Elementary School, which police closed to students and staff Friday as a precaution.
Katherine Park, 27, who lives next door to the victim's house, said her boyfriend woke her after hearing the shots.
Park doesn't know the residents of the rental house, but she said she called police about a loud party there two weeks ago after someone threw a bottle into her yard.
"They're a little rowdy but relatively quiet for undergraduate students," she said.
Noor Fateh, 20, a Hofstra sophomore who lives in one of the California Avenue rental homes, said he returned home early Friday to a sea of police cars.
"I live very close to this," he said, surveying the crime scene. Fateh, of Los Angeles, said the shooting "is really shocking to the entire community."
David Anglin, who lives two houses away, was surprised and saddened by the news.
"This is my block," he said. "This is where I live. I never heard of anything like this. You don't want to hear something like this happening to anybody."
Hofstra said counseling services are available for students and that the school has set up a call center for parents and students. The number is 516-463-5800.
With Candice Ferrette, Ellen Yan and Bill Mason