A fire broke out at 4044-46 Walnut St. on Saturday evening, causing no injuries but displacing three Penn students.

According to Director of Operations and External Affairs at the Division of Public Safety Stefanie Cella, the cause of the fire has yet to be determined. The Philadelphia Fire Marshal's Office could not be reached for comment.

The job was called in to 9-1-1 at 5:11 p.m.

The Philadelphia Police and Fire departments, as well as the Penn Police Department and Fire and Emergency Services Chief Gene Janda responded to the call within two minutes.

The fire was extinguished in about 20 minutes, only damaging the building, Cella wrote in an e-mail.

College sophomore Anita Deshpande, who witnessed the fire, said she returned to her house on the 4000 block of Walnut Street on Saturday to find an "ambulance on stand-by" on her street and three male students leaning on her fence. The students informed her that there had been a fire in their apartment building.

They reportedly said that while they were barbecuing on their roof, the bottom of the grill collapsed, igniting the fire. This has not been confirmed by officials.

"There is a sign on the door saying that nobody is living there now," Deshpande said of the apartment building.