Doorbell camera footage captured the beginning of a seven-floor partial building collapse at a parking garage in Philadelphia, leaving one person dead, two injured, and two others missing.

A garage under construction for Children's Hospital of Philadelphia employee parking partially collapsed along Grays Ferry Avenue.

"Errors happen. It could be design-based, it could be construction-based, it could be material deficiency," said Dr. Abi Aghayere, Professor of Structural Engineering at Drexel University.