AMSTERDAM, N.Y. — A ceremony for the victims of the limousine crash that killed 20 people ended with participants lifting candles above their heads to signal unity and perseverance.

Over 1,000 people jammed a riverside park in Amsterdam, New York, for Monday night's vigil as victims' relatives tried to come to grips with the tragedy that happened as a group of friends and family were on their way to a 30th birthday party.

The supersized limo ran a stop sign and hit a parked SUV on Saturday in Schoharie.

Authorities have yet to say how fast the limo was going or determine why it failed to stop and sped off the road at the bottom of a long hill.

The 19-seat vehicle had at least some seat belts, but it was unclear whether anyone was wearing them, National Transportation Safety Board Chairman Robert Sumwalt said.

The crash about 170 miles north of New York City came three years after another deadly stretch-limo wreck in New York state spurred calls for Gov. Andrew Cuomo to examine such vehicles' safety. There is no evidence the state took any steps to do so.

Some relatives of the dead shed tears as local officials expressed solidarity with them.

U.S. Rep. Paul Tonko, a Democrat from Amsterdam, told a crowd that spilled onto a bridge spanning the Mohawk River, "We are crushed with you, we are crushed for you."

Some relatives shed tears as a woman sang "Amazing Grace." The ceremony ended with everyone lifting their candles above their heads in unity.

The wreck killed two pedestrians and all 18 people in the limousine, including four sisters who were headed with friends and relatives to a brewery for a party for one of the sisters.

The four sisters' aunt, Barbara Douglas, said they had felt "they did the responsible thing getting a limo so they wouldn't have to drive anywhere."

"My heart is sunken. It's in a place where I've never felt this type of pain before," said Karina Halse, who lost her 26-year-old sister Amanda.

Authorities haven't released the driver's name, but multiple law enforcement officials identified him as Scott Lisinicchia.

"The investigation is STILL going on and the facts are not verified," his niece, Courtney Lisinicchia, wrote on Facebook.

The state moved to shut down the owner, Prestige Limousine, as state and federal authorities investigated the cause of Saturday's wreck in Schoharie. The company said it was taking its cars off the road while conducting its own probe into the crash.

People mourn at the site of the fatal limousine crash in Schoharie, New York on Oct. 8, 2018. Stephanie Keith / Getty Images

Investigators plan to examine the mangled limo's data recorders and mechanical systems as well as the road, which has a history as a danger spot. They are also looking into the driver's record and qualifications and conducting an autopsy to see if drugs or alcohol were factors.

But officials already saw some red flags, Cuomo said: The driver didn't have the necessary commercial license, and the vehicle failed a state inspection that examined such things as the chassis, suspension and brakes.

"In my opinion, the owner of this company had no business putting a failed vehicle on the road," the governor said while attending a Columbus Day Parade in New York City. "Prestige has a lot of questions to answer."

He also said the limo — built by cutting apart a heavy-duty SUV and lengthening it — had been created without federal certification, though NTSB officials said they hadn't yet determined whether the vehicle met federal standards.

Prestige Limousine issued a statement Monday expressing condolences to victims' families and saying it was conducting "a detailed internal investigation" while also meeting with state and federal authorities.

The Gansevoort, New York-based company said it pulled its cars from the road voluntarily. But state police say they seized four Prestige cars, including the one that crashed.

Federal records show the company has undergone five inspections in the past two years and had four vehicles pulled from service.

In inspections Sept. 4, the company's limos were cited for defective brakes, lack of proper emergency exits, flat or balding tires, defective windshield wipers, and other maintenance problems.

Federal transportation records show Prestige is owned by Shahed Hussain, who worked as an informant for the FBI after the Sept. 11 attacks, infiltrating Muslim groups by posing as a terrorist sympathizer in at least three investigations. In one case, he helped convict men accused of plotting to bomb New York synagogues.

His role at the FBI was assailed by civil liberties groups, who accused him of helping the FBI entrap people. Asked Monday about Hussain, the FBI wouldn't comment.

The limousine, built from a 2001 Ford Excursion, ran a stop sign at a T-shaped intersection at the bottom of a hill and slammed into an unoccupied SUV.

Family members sign a banner in memory of their loved ones during a candlelight vigil for the victims of a limousine accident in Amsterdam, New York. Cindy Schultz / Reuters

Investigators have yet to determine whether the driver tried to brake. The crash left no visible skid marks, but that might be due to misty weather or anti-lock brakes, Sumwalt said.

The crash appeared to be the deadliest land-vehicle accident in the U.S. since a bus full of Texas nursing home patients fleeing 2005's Hurricane Rita caught fire, killing 23. Saturday's wreck was the nation's deadliest transportation accident of any kind since a 2009 plane crash near Buffalo, New York, killed 50 people.

Factory-built limousines must meet stringent safety regulations. 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.

Few federal regulations govern limos modified after leaving the factory. Regulations often vary by state.

"It certainly is the Wild West out there when it comes to limousines and stretch vehicles," said National Safety Council CEO Deborah A.P. Hersman.

Ford said in a statement that it has never made its own stretch version of the Excursion. It did certify outside companies to modify them to Ford specifications for up to 14 seats during the 2001 model year, but it wasn't clear who modified the SUV that crashed Saturday.

After a stretch limousine was T-boned on New York's Long Island in 2015, killing four women, a special grand jury implored Cuomo to examine the safety of such vehicles.

It appears the task force was never formed, and nearly three years after the grand jury's recommendation, it was unclear what, if anything, Cuomo's administration did in response.

"I don't know if there was a task force set up," the governor said Monday, while suggesting that Saturday's crash didn't necessarily point to a need for more regulation.

"Sometimes, people just don't follow the law" that already exists, he said. "And that may very well be what happened here."

The New York grand jury report recommended state lawmakers require stretch limousines that seat nine or more passengers to meet the stricter inspection regulations that apply to buses.

Lawmakers, including Democratic Sen. Chuck Schumer of New York, asked federal officials several years ago to raise safety standards for stretch limos modified after manufacture.