Twenty people in upstate New York lost their lives over the weekend in what is now being called the deadliest transportation crash in nearly 10 years.

Eighteen people inside a limousine and two standing in a parking lot were killed when the limo driver collided with the bystanders after running a stop sign and appearing to lose control of the vehicle.

The scale of the tragedy is immeasurable for the families now grappling with loss. Local paper Times Union reports the limo was packed with a close-knit group of friends celebrating a 30th birthday. Though officials have not released identities, the uncle of one of the victims told the paper multiple families lost more than one child. The Times Union reports two sets of newlyweds, four sisters, and two brothers were among the dead. A third married couple in the limo left behind two small children under 5 years old. A

has been set up for the now-orphaned little girls.

Everyone in the limo had grown up together, the uncle said.

"Twenty fatalities is just horrific," said National Transportation Safety Board chairman Robert Sumwalt in a briefing Sunday afternoon. "I've been on the board for 12 years, and this is one of the biggest losses of life that we've seen in a long, long time."

Indeed, it was the deadliest transportation-related accident in the United States since February 2009 when a plane crash killed 50. That crash also happened in upstate New York.

Investigators are still trying to figure out how the crash happened, but based on evidence and witness accounts, authorities believe the limo was speeding downhill as it approached the junction of State Route 30 and State Route 30A. The limo driver failed to stop and drove into two people standing outside the Apple Barrel Country Store, a cafe popular with leaf-peepers located across the street from the intersection. The vehicle kept going, hitting at least one car in the parking lot before going off the road. A witness said the car that was hit in the lot was damaged nearly beyond recognition.

"I couldn't believe it when I came out of the woods," he told the Times Union. "This is terrible, terrible, terrible."

Another bystander said the crash sounded like an explosion.

Police confirmed Sunday no one was inside the parked car and that everyone killed was either in the limo or standing outside the cafe.

show a white stretch SUV limo entangled in trees off the side of the road.

The intersection of the two state roads is notoriously dangerous to those living in the Schoharie area. Route 30 heading towards the intersection is long, windy and is a fairly steep downhill.

Apple Barrel Country Store posted to its Facebook page that it was receiving donations for area volunteer emergency services.

As you may be aware, there was a horrific accident in front of our business today. First, we want to thank all of the... Posted by Apple Barrel Store + Cafe on Saturday, October 6, 2018

Yes, are open today. And could use your hugs. Donations are be accepted for our local emergency services. We are doing... Posted by Apple Barrel Store + Cafe on Sunday, October 7, 2018

WATCH: Officials give an update after a horrific crash in upstate New York kills 20. A wedding party was reportedly in the limo involved in the crash. https://www.kktv.com/content/news/20-killed-in-crash-involving-limo-reportedly-carrying-wedding-party-in-upstate-New-York-495385921.html Posted by KKTV 11 News on Sunday, October 7, 2018