U.S. President Donald Trump has ordered more "extreme vetting" of immigrants after police detained an Uzbek man as a suspect in what they called a "terrorist attack" that killed eight people in New York City on October 31.
It was the first deadly terrorist attack with a vehicle in New York City since the September 11, 2001, attacks on the World Trade Center.
"I have just ordered Homeland Security to step up our already Extreme Vetting Program. Being politically correct is fine, but not for this!" Trump tweeted after declaring earlier that the attack was perpetrated by "a very sick and deranged person."
New York police said the suspect, who police shot and detained at the scene, used a rented van to drive into pedestrians and cyclists on a bike path near where the Twin Towers of the World Trade Center once stood.
Police sources identified the suspect as a 29-year-old Uzbek national named Sayfullo Habibullaevic Saipov, who came to the United States legally in 2010.
His immigration status was not immediately clear, according to police sources.
Witnesses said Saipov shouted out "Allahu akbar" or "God is greatest" after crashing the van into pedestrians and a school bus.
In Tashkent, Uzbek President Shavkat Mirziyoev said in a statement posted to the Foreign Ministry's website on November 1 that his government "is ready to use all forces and resources to help in the investigation of this act of terror."
WATCH: A bystander caught the arrest on camera of the man suspected of using a vehicle to run down people on a bicycle path in New York City, killing at least eight.
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New York Attack Suspect's Arrest Caught On Video
While U.S. authorities have said Saipov is the only suspect in what appeared to be a "lone wolf" attack, media reported that investigators found a handwritten note Saipov apparently left in the van claiming he carried out the attack in the name of the Islamic State (IS) extremist group.
"This was an act of terror, and a particularly cowardly act of terror, aimed at innocent civilians, aimed at people going about their lives who had no idea what was about to hit them," Mayor Bill de Blasio told a news conference.
An Uzbek immigrant in the United States who said he knew Saipov, Mirrakhmat Muminov, told RFE/RL that Saipov lived in Akron, Ohio, before moving to Florida in 2013, and worked for many years as a truck driver.
He said Saipov had a wife and two children and was a native of Tashkent. He described the suspect as somewhat "aggressive," but said he was not very religious before he went to Florida.
Muminov said he thought Saipov became more radical because he was getting information from Islamic extremists through the Internet.
Still, Muminov said no one thought Saipov was capable of committing a terrorist attack. He said he was "shocked" by the incident and couldn't imagine what kind "of monsters were in his head."
Sayfullo Saipov is the suspect in the attack on New York.
Uber said in a statement that Saipov had worked as a driver for the ride service before the attack. The company said it was "horrified by this senseless act of violence" and had banned Saipov from the Uber app.
Saipov was reportedly arrested in Missouri last year over a traffic fine.
A spokesperson for the U.S. Department of Homeland Security called the Manhattan incident an "apparent act of terrorism."
Authorities said five Argentinians and one Belgian were among the eight people killed in the attack.
Over a dozen people were injured, and 11 people had serious but not life-threatening injuries, according to emergency services.
Police said the suspect used a van rented from a New Jersey Home Depot hardware store in his rampage, and after crashing the vehicle, he emerged wielding what they said were fake guns.
Video posted by NBCNewYork.com showed Saipov after crashing the van running through traffic with what appeared to be a BB gun and paintball gun.
Authorities said police shot Saipov at the scene, took him into custody, and transported him to New York's Bellevue Hospital for treatment of an injury to the abdomen that was not deemed to be life-threatening.
New York Governor Andrew Cuomo described it as a "lone wolf" attack, saying there is no evidence to suggest it was part of a "wider plot or wider scheme."
Cuomo ordered increased security at New York's airports, bridges, tunnels, and mass transit systems, and directed that the lights on the spire of 1 World Trade Center be lit in red, white, and blue in honor of "freedom and democracy."
WATCH: Mobile phone footage shows the first moments after a New York school bus was hit by an Uzbek driver. Two staff and two children were injured on the bus. (AP)
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New York School Bus Hit By Uzbek Suspect
Similar To Attacks In Europe
Similar attacks using vehicles to crash into pedestrians have killed dozens of people in Europe during the last 16 months.
in July 2016, a man drove a large truck into a crowd celebrating Bastille Day in the French city of Nice, killing 86 people and injuring hundreds more. The IS group claimed responsibility for the attack.
Five months later, a Tunisian asylum seeker who had pledged allegiance to IS plowed a truck into a crowded Christmas market in central Berlin, killing 12 people and injuring 48.
In April of this year, a failed asylum seeker from Uzbekistan careened down a busy street in a truck in central Stockholm, crashing into a department store and killing three people in what the prime minister called a terrorist attack.
And on August 17, a driver rammed his van into crowds in the heart of Barcelona, killing 13 people, in an attack authorities said was carried out by suspected Islamist militants.
With reporting by AFP, AP, Reuters, dpa, NBCNewYork.com, ABC News, and Pete Baumgartner