PHILADELPHIA — Authorities on Sunday were investigating how a metal security grate detached and fell from the facade of an Italian ice shop, killing a 3-year-old girl in front of dozens of people who tried to rescue her.

The girl, Wynter Larkin, was with her mother at the Rita’s Water Ice store in north Philadelphia, where a fundraiser for a sorority and fraternity was underway Saturday, when she was trapped under the falling grate, police and witnesses said.

Members of the Omega Psi Phi fraternity rushed to get the girl out from under the grate and give her CPR, witnesses said. The girl was taken to Hahnemann University Hospital, where she was pronounced dead.

“It took about 20 to 30 men to get that awning off of the baby,” witness Tracey Stanford said. “When they finally got it up off of her, she was just lying there, lifeless.”

Carlton Williams, commissioner of the Department of Licenses and Inspections, said in an emailed statement that there were no open violations at the store and no reported problems with its security gate.

Nevertheless, police Inspector Christine Coulter said the investigation was broadening to all other buildings on the block and, in particular, their security grates. But at this point, Coulter said, the accident appears to be “a horrible tragedy.”