A terrible accident. That's how police are describing the death of 30-year-old woman who plunged early Friday from a 12th-floor balcony at a posh waterfront apartment building in South Philadelphia.

The woman - who worked at Club Risque but whose name police have not released - dropped her cellphone about 4 a.m. from a friend's balcony at the Dockside condominiums on the 700 block of South Christopher Columbus Blvd.

The phone had fallen onto a neighbor's patio eight floors below, police said.

The woman and the man she was visiting called building security and asked if they could wake the 4th-floor residents in an effort to retrieve the phone, said Capt. Laurence Nodiff of South Detectives.

Noting the late hour, and not wanting to disturb anyone, security said they would try and locate phone in the morning, Nodiff said.

It was unclear exactly how she fell, Nodiff said, but "at one point, she was looking over balcony for her phone."

Investigators have interviewed the woman's friend and conducted a search warrant of the apartment, finding no signs of foul play. The balcony railing was intact, Nodiff said.

"We believe her fall was accidental," he said.

A medical examiner will conduct an autopsy over the weekend, Nodiff said. Toxicology reports to determine of alcohol played a factor in the accident will take 4-6 weeks, he said.