CAMBRIDGE (CBS) – A 15-year-old girl is dead after an assault on a Cambridge sidewalk. Investigators said she was thrown to the ground and hit her head.

Now, her friends are reeling and the district attorney’s office is looking for any witnesses.

READ MORE: 34-Year-Old Man Dies After Hit-And-Run In Bridgewater

“She died at a young age and I feel bad for her family and what they have to go through,” said student Sanaa Lahens.

On Tuesday, the district attorney called for witnesses to come forward to help ID someone who was in the area at the time on bicycle.

“What we know at this point is a 15-year-old was in route to a friend’s house and at some point is seen being thrown to the ground on Cambridge Street around the 700 block,” said Middlesex District Attorney Marian Ryan.

READ MORE: Franklin Man Allegedly Driving 142 MPH Arrested In New Hampshire

“This young girl, on the ground, unresponsive,” said Jacueline Soza, who saw the aftermath outside Portugalia restaurant Sunday night.

Portugalia’s owner says the young woman was unconscious and bleeding, as people inside rushed to help.

The owner of Portugalia’s explained where the girl was assaulted. (WBZ-TV)

She died a day later. Friends at Cambridge Rindge and Latin School, where she took summer classes, said the awful news spread quickly on social media.

“Someone could talk to you on Thursday and could die in two days, it’s just unexpected,” said student Kamaal Waterman.

MORE NEWS: 800 Nurses At St. Vincent Hospital In Worcester Preparing To Strike

Tips can be left by contacting Cambridge Police at (617) 349-3300. You can also provide information anonymously by calling the Cambridge Police Tip Hotline at (617) 349-3359 and leave a message.

Louisa Moller