Sen. John Heinz and 6 others died when a plane and helicopter collided on this week in Philly history

Around noon on a sunny, 59-degree spring afternoon on April 4, 1991, a helicopter and a plane collided over Merion Elementary School.

In the end, 52-year-old U.S. Sen. John Heinz, a Republican from the famously wealthy Pittsburgh family, was killed along with four pilots and two schoolchildren.

And untold hundreds, who bore witness to a living nightmare, would never be the same.

Heinz, a favorite to be the Keystone State’s next governor, was aboard a piper plane navigated by two Central Pennsylvania pilots.

They were returning from a news conference in Williamsport, closing in on their destination, Philadelphia International Airport, when the pilots reported issues with the plane’s landing gear.

Two pilots in a nearby helicopter heard the call and volunteered to fly toward the plane to see if they could offer assistance.

And then the two aircraft collided in clear skies, creating a fireball that hurled to the earth.

Thick smoke and bright flames tailed pieces of wreckage that sporadically fell, thankfully sparing the gray stone school building on Bowman Avenue and those inside it.

Outside the building, frightened children scattered as teachers and administrators attempted the wrangle the screaming herd. Parents and guardians rushed to the school, desperately seeking reassurance that their children were OK.

Airplane pilots Trond Stegen and Richard Shreck and helicopter pilots Charles Burke and Michael Pozzani were killed.

As was Heinz.

First graders Rachel Blum and Lauren Freundlich were killed by burning debris that rained down over the schoolyard.

When their parents arrived, the school principal was physically unable to tell them the tragic news.

“I couldn’t get the words out of my mouth,” he told The Inquirer a year later.

At least five other people on the ground, including three children, were injured.

One of the injured, a 7-year-old student from Wynnewood, was severely burned by jet fuel that splattered the schoolyard.

His burns stretched from his mid-calf to his chin, according to an Inquirer report.

The National Transportation Safety Boarded blamed the pilots.

The crash and seven deaths were the result of “poor judgment” by pilots in both aircrafts, federal investigators later determined. The plane pilot showed bad judgment by allowing the helicopter to dangerously inspect its landing gear, and the helicopter pilot showed bad judgment by trying to get close enough to inspect in the first place.

Investigators also said the plane should have attempted an emergency landing.

In 1991, Teresa Heinz, the senator’s widow who would later marry U.S. Sen. John Kerry, sued the owners of the airplane and helicopter.

The wrongful-death lawsuit was settled for $15 million in 1997.

A small memorial grove of trees and benches was added at the school, as were plaques for the responders, and those two little girls.