NEW YORK — The Uzbek immigrant accused of mowing down people along a bike path near the World Trade Center left a handwritten note referring to the Islamic State group and had been radicalized in the U.S., New York's governor said Wednesday.

Investigators, meanwhile, were at the hospital bedside of 29-year-old Sayfullo Saipov, working to extract information about the truck attack Tuesday afternoon that left eight people dead and 11 seriously injured, a law enforcement official said.

The official, who was not authorized to discuss the investigation and spoke on condition of anonymity, said Saipov was lucid after surgery for wounds suffered when he was shot by police.

Authorities found a note inside the rented Home Depot pickup truck.

Gov. Andrew Cuomo said the suspect was a "depraved coward" who tried to create terror. He gave no details on the note except to say it referred to the Islamic State.

"He was associated with ISIS and he was radicalized domestically," he said on CNN. "It's not the first time. It's a global phenomenon now."

In a number of recent extremist attacks around the world, the assailants were found to have been inspired but not actually directed by the Islamic State, and in some cases never even made contact with the group.

In Tuesday's attack, Saipov hurtled down the bike path, running down cyclists and pedestrians, then crashed into a school bus, authorities said. He was shot in the abdomen after he jumped out of the vehicle brandishing air guns and yelling "God is great!" in Arabic, they said.

Mayor Bill de Blasio called it "a cowardly act of terror."

A roughly two-mile stretch of highway in lower Manhattan was shut down for the investigation. Authorities also converged on a New Jersey apartment building and a van in a parking lot at a New Jersey Home Depot.

Police and the FBI urged members of the public to come forward with any photos or video that could help.

In the past few years, the Islamic State has been exhorting followers to use vehicles or other close-at-hand means of killing people in their home countries. England, France and Germany have seen deadly vehicle attacks in the past year or so.

President Donald Trump railed against the Islamic State on Twitter and declared "Enough!" and "NOT IN THE U.S.A.!"

On Wednesday, the president took a swipe at the Senate's top Democrat, saying Saipov came to the U.S. under a visa lottery program — "a Chuck Schumer beauty." He urged tougher immigration measures based on merit.

Schumer, who represents New York, said in a statement that he has always believed that immigration "is good for America."

The victims reflected a city that is a melting pot and a magnet for visitors: One of the dead was from Belgium. Five were from Argentina and were celebrating the 30th anniversary of a school graduation. The injured included students and staffers on the school bus.

New Yorkers woke to a heavy police presence Wednesday outside the World Trade Center and at other locations around the city.

Runners and cyclists who use the popular bike path for their pre-dawn exercise were diverted away from the crime scene by officers stationed at barricades just north of where the rampage began.

Dave Hartie, 57, who works in finance, said he rides his bike along the path every morning.

"It's great to be in the city and have that kind of peace," he said. As for the attack, he said, "It's the messed-up world we live in these days. Part of me is surprised it doesn't happen more often."

Law enforcement officials who were not authorized to discuss the investigation and spoke on condition of anonymity said the slight, bearded attacker is from heavily Muslim Uzbekistan and came to the U.S. legally in 2010. He has a Florida driver's license but may have been staying in New Jersey, they said.

Records show Saipov was a commercial truck driver who formed a pair of businesses in Ohio. He had also driven for Uber.

Associated Press writers Sadie Gurman in Washington; Jake Pearson, Tom Hays, Adam Geller, Jennifer Peltz, Karen Matthews, Kiley Armstrong and Tom McElroy in New York; Shawn Marsh in Trenton, New Jersey; Michael Balsamo in Los Angeles; Jon Gambrell in Dubai, United Arab Emirates; and Michael R. Sisak in Philadelphia contributed to this report.