Mourners pay their respects by a makeshift memorial of flowers that lie at the scene of Saturday's limousine accident in Upstate New York, in Schoharie, New York, U.S., October 8, 2018.
He added, however, that officials did not yet know the cause of the accident - whether it was an issue with the vehicle or a driver error.
"The owners of the company had no business putting a failed vehicle on the roadway", he said. Before Amanda Halse received her sister's reply, she died in the crash.
The National Transportation Safety Board said members of its "go team" were at the crash site to investigate what happened and possible factors, including road and vehicle conditions.
Twenty people were killed when the SUV-style stretch vehicle careened out of control on Saturday in Schoharie, a town in NY state, killing all 18 occupants and two pedestrians.
And the lives of those inside- some of whom were newlyweds, some of whom were siblings and others who were parents-would be tragically cut short.
People gathered Monday night in Amsterdam to honor the 20 victims of the deadly Schoharie limousine crash.
Before the limousine crashed, on the way to a birthday party, one of the victims, Erin McGowan, texted a friend that the limousine was in bad condition and appeared to have motor trouble, the New York Times reported.
McGowan's aunt, Valerie Abeling, told CNN her niece had texted a friend saying the company had sent the stretch limousine to replace a vehicle that had broken down.
Like the Steenburgs, the McGowans were married in June. She and her three sisters - Mary Dyson, Allison King and Abby Jackson - and her husband, Axel, and his brother, Rich, all died, relatives told The New York Times.
There were newlyweds and young couples and four sisters, all on their way to revel at an upstate NY brewery.
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"There have been tractor trailers that have come barreling down that hill and it was a miracle they didn't kill somebody", Tavenner said.
"They did the responsible thing getting a limo so they wouldn't be driving", Barbara Douglas, an aunt of the four sisters, told NBC News. They say the 2001 Ford Excursion limo had been extended over the years to accommodate more passengers.
In Mrs Steenburg's last ever Facebook post, dated on 3 October, she thanked her husband for "being so kind and loving".
Eric Steenberg, brother to Axel Steenberg, who was married to one of the four sisters, said that another brother, Rich Steenberg, was also in the limo.
Mary was a veteran of the Army who had been working at the Watertown office for Upstate Construction Services, according to the local news station WNNY-TV.
Matthew W. Coons, Rachael K. Cavosie and Michael C. Ukaj were also killed. Their godfather, Patrick Cushing, also was killed.
The Jacksons left behind two daughters, Archer and Elle, ages 4 and 1. The close-knit group included newlyweds, artists, athletes and young parents.
Ms Abeling said of the victims: "She was a handsome, sweet soul; he was too".
"It's a disgusting tragedy, and there's no words to describe how we feel", Abeling said.
Tavenner said the New York Department of Transportation outlawed heavy trucks on the hill in recent years because of instances when runaway trucks lost their ability to brake down the steep grade. Five women out for a bachelorette party were killed in 2013 when their stretch limo caught fire in Northern California because of friction between the driveshaft and the rear floorboard. But luxury cars converted to limos, like the one in Saturday's crash, often lack such safety components as side-impact air bags, reinforced rollover protection bars and accessible emergency exits.