U.S. President Donald Trump ordered more "extreme vetting" of immigrants after police detained an Uzbek national 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 such attack in New York since the September 11, 2001 attacks, and the first time the United States has been struck with a vehicular attack like those that have occurred recently in Europe.
"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, mowed down pedestrians and cyclists on a bike path near the World Trade Center.
Police sources identified the suspect as 29-year-old Uzbek national named Sayfullo Habibullaevic Saipov, who media reported came to the United States in 2010.
Witnesses said Saipov shouted out "Allahu Akbar" or "God is Great" as he rampaged through the streets after crashing a rented van into the pedestrians and a school bus.
While authorities have said Saipov is the only suspect in what appeared to be a "lone wolf" attack, media reported that investigators found a hand-written note Saipov apparently left in the van claiming he carried out the attack in the name of the Islamic State 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 following the attack.
An Uzbek immigrant in the United States who said he knows 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.
Muminov said Saipov has a wife and two children and is a native of Tashkent. He described the suspect as somewhat "aggressive," but said he was not too religious before he went to Florida.
Muminov said he thinks Saipov became more radical because he was getting information about Islam through the internet.
Still, Muminov said no one thought Saipov was capable of committing a terrorist attack. He said he is "shocked" by this incident and can't imagine what kind "of monsters were in his head."
A spokesperson for the U.S. Department of Homeland Security called the incident an "apparent act of terrorism."
Authorities said five Argentinians and one Belgian were among the eight killed in the attack.
Over a dozen people were injured, and eleven 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."
Similar attacks using vehicles to mow down pedestrians have killed dozens of people in Europe in the last year.
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 Islamic State claimed responsibility for the attack.
Five months later, a Tunisian asylum seeker who had pledged allegiance to Islamic State plowed a truck into a crowded Christmas market in central Berlin, killing 12 people and injuring 48.
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.
Based on reporting by AFP, AP, Reuters, dpa, NBCNewYork.com, ABC News, and RFE/RL correspondent Pete Baumgartner