A mid-air collision of a Cessna 172 and a Pacific Southwest Airlines (PSA) Boeing 727 brought both planes crashing into a North Park neighborhood on September 25, 1978. 144 lives were lost including 7 people on the ground and the two people in the Cessna. More than 20 residences were damaged or destroyed. At the time, it was the worst air disaster in U. S. history. The fire went to four alarms, committing 60% of the on-duty force of the Department as well as several outside agencies. Droves of off-duty firefighters voluntarily reported back to their assigned stations or to the crash scene to help where they could.