Updated

Authorities in Pennsylvania late Thursday responded to a massive fire at a nursing home that required hundreds of residents to be evacuated.

CBS Philadelphia reported that fire crews were called to Barclay Friends Nursing Home at about 11 p.m. local time. 

The fire quickly spread to multiple buildings and flames could be seen shooting from the roofs and windows of the structures. Residents were forced to evacuate outside into the cold. News helicopter video showed dozens of residents lined up along the street, wrapped in blankets, many of them in wheelchairs.

Chester County emergency officials said at least 20 people were taken to area hospitals for treatment. The extent of their injuries was not immediately known.

A spokeswoman for Main Line Health said area hospitals also were providing shelter to some additional residents of the senior living community.

A cause of the fire was still under investigation.

Emergency crews were seen transporting people from the scene.

The Associated Press contributed to this report