On 9:01 a.m. on September 25, 1978, a Boeing 727 and Cessna 172 collided over urban San Diego, creating one of the worst air disasters in California, and the deadliest in the United States at the time.

After the collision, the Boeing and all 135 of its passengers impacted the ground at a near-vertical angle at over 300 miles per hour, killing all on board, seven on the ground, and injuring an additional nine people on the ground. The Cessna’s wreckage also came down nearby, killing two on board.

The impact destroyed a number of homes in the area, and almost all of the first responders to the crash site suffered from post-traumatic stress disorder after working the disaster and witnessing the carnage in the weeks following.

A plaque at the San Diego Aerospace Museum a nearby library serve as memorials to those killed. The only clue at the actual location is a slightly wavy texture as you drive over it.

Still, every year on September 25, the local news and family members hold a memorial service in remembrance of the souls lost that day.