One victim's relative said the hired limo was a replacement for "some kind of bus" that was supposed to take the group on a tour of wineries and breweries for Amy's 30th birthday party.
The NTSB will look at a number of factors, including the driver's fitness, whether fatigue was an issue, the company's compliance with state and federal regulations and its record of prior crashes, Sumwalt said. The impact killed two pedestrians standing nearby.
Robert Sumwalt, chief of the National Transportation Safety Board (NTSB), told CNN that the accident should be "a wake-up call" for limousine safety.
Police said everyone inside the limousine, including the driver, died in the crash, and all those killed were adults.
The 19-seater limo ran a stop sign and hit a parked SUV on Saturday in Schoharie (skoh-HAYR'-ee).
The intersection had been redone in 2008 because of a fatal accident there, said Jessica Kirby, who is managing director of the Apple Barrel Country Store. Schoharie Town Supervisor Alan Tavenner said Sunday the New York Department of Transportation had in recent years outlawed heavy trucks on the hill because of instances where runaway trucks lost their ability to apply the brakes down the steep grade. He said the limo was carrying out-of-towners during a busy tourist weekend, Stone Fort Days.
Image copyright Facebook/ Erin McGowan Image caption Erin and Shane McGowan married last June 'I love you more than words can say!'
"Twenty fatalities is just horrific", he said. "This is the most deadly transportation accident or crash that we've seen on USA soil since February of 2009".
It is unclear how many other people, if any, were injured. Some 20 minutes later, the limousine came over a steep hill and headed down toward a T-shaped intersection in Schoharie.
Bill Waterson, who said he was invited to attend the wedding that the limousine was travelling from, said he could not believe what he had witnessed, describing it as "terrible", the Albany Times Union reported.
Karina Halse told The Associated Press that her sister, a waitress, had texted her just before getting into the limo.
Abeling said her niece's new husband, 30-year-old Shane McGowan, had also been in the limousine.
"It's tragic. awful. I can't even begin to even explain". Jackson was a special education teacher in Amsterdam, said Santabarbara, who represents the part of NY where the crash happened. "Our lives have been changed forever".
Cushing worked in technology services for the New York State Senate, according to a statement from Sen.
The crash "sounded like an explosion", said Linda Riley, of nearby Schenectady, who was on a shopping trip with her sisters and had been in their parked auto at the time at the store, which sits near a T-junction of two NY state highways.
The sister of one of the women killed on Saturday said her heart is "sunken" and she's in a "place where I've never felt this type of pain before".
Axel's 34-year-old brother was also killed in the crash.
Authorities on Sunday didn't release names of victims or other specifics, but state police set up a hotline for family members.
The limousine then slammed into a parked, unoccupied 2015 Toyota Highlander.
"They were both just soul mates because they just radiated love and beauty and how a marriage should be", Valerie Abeling told CNN.
"They had everything going for them", Abeling said.
Needless loss of life is always tragic, but the concentration of loss in this close-knit group of people is deeply so.
Photos from Schenectady Daily Gazette photographer Peter Barber showed a white van-style stretch limousine lodged in a ditch, along with police and emergency vehicles that had converged on the scene.
A manager of the store said the limo was coming down the hill at "probably" 60 miles per hour, the New York Times reported. Investigators have not yet said whether any of the victims were wearing seat belts.