At a press conference this morning, Mayor Bill de Blasio excoriated the suspect accused of driving a truck down the West Side Highway bike path yesterday, killing 8 people and injuring 12. "This was an attack on the United States of America, an attack on New York City, an attack on our people, and it was the definition of terrorism," he said. Still, de Blasio urged New Yorkers to carry on as normal, citing the 1 million people who attended last night's Halloween parade in Greenwich Village and that 2.5 million people expected to cheer on the NYC Marathon on Sunday.

"This violence was an effort to make us blink, and we won't blink," de Blasio said. "We won't change."

Officials, meanwhile, confirmed the suspect, 29-year-old Sayfullo Saipov, had been planning the attack "for weeks."

FDNY Chief Daniel Nigro confirmed the eight fatalities in the attack, noting that six victims were visiting from abroad. Of the 12 injured, Nigro said three have been released from area hospitals, four are hospitalized in critical but stable condition, and five are hospitalized in serious condition. Injuries include head injuries, neck, back and chest trauma, trauma to arms and legs, and a bilateral amputation.

Though officials warned the information was still preliminary, NYPD Deputy Commissioner of Intelligence & Counterterrorism John Miller said Saipov "had been planning this for a number of weeks," and that he "did this in the name of ISIS," as indicated by handwritten notes recovered at the scene that suggested "the Islamic State would endure forever."

"He seems to have followed, almost exactly to a T, instructions ISIS has put out on social media to followers as to how to carry out such an attack," Miller said.

Miller also noted Saipov rented the truck he used to kill and injure his victims from a Home Depot location in Passaic, NJ at around 2:06 p.m. yesterday. He drove into Manhattan over the George Washington Bridge, taking the West Side Highway south and then pulling onto the bike path at West Houston Street shortly after 3 p.m., plowing into pedestrians and cyclists as he drove toward Chambers Street. (The Times has an interactive graphic charting his path.) Saipov only stopped when he struck a school bus, then exited the truck carrying what initially appeared to be weapons, but were later determined to be a pellet gun and paint gun.

Saipov was shot in the abdomen by Officer Ryan Nash, a 28-year-old cop and five-year member of the force, who had been responding to an unrelated incident at Stuyvesant High School when he and his partner were alerted to what was then described as a vehicular accident on the West Side Highway.

"He was a hero," Governor Andrew Cuomo, who also attended today's press conference, said. "The NYPD is not just the leadership, it's the men and women who are out there every day, who are on the first line. I think Officer Nash really showed how important they are, and how talented and how brave."

Miller noted that Saipov, a legal resident of the United States who immigrated here from Uzbekistan in March of 2010, had never been the subject of an NYPD or FBI investigation, but officials are looking into whether or not he had connections with subjects of other investigations. Saipov is currently in custody and under arrest at Bellevue Hospital, where Miller says investigators are waiting to hear about his condition.

De Blasio, Cuomo, and NYPD Commissioner James O'Neill said they had all received calls from acting Secretary of Homeland Security Elaine Duke offering any federal assistance needed. De Blasio also received a call from Tom Bossert, the White House's Homeland Security Advisor. None had received a call from President Donald Trump, though both Cuomo and de Blasio said that didn't bother them. "Two senior officials called promptly and offered help and I think that was appropriate," de Blasio said. "No one up here wants to politicize any of this."

Still, Cuomo called out the President for his tweets today claiming the Department of Homeland Security needs to "step up" its "Extreme Vetting Program," and that "[b]eing politically correct is fine, but not for this!"

"The president's tweets, I think, were not helpful. I don't think they were factual, I think they tended to point fingers and politicize the situation," Cuomo said. "You play into the hands of terrorists to the extent you disrupt and divide and frighten people in this society. The tone now should be exactly the opposite."

Officials say there will be added security in the city in the coming days, especially at the airports, in the tunnels, at Penn Station, in the subways, and on the marathon route on Sunday. Measures include added sand trucks, blocker vehicles, rooftop snipers, heavy weapons teams, and explosive detecting canines. "I don't want anyone to draw any inference from that. We don't know anything, we're not responding to anything, it's just a precaution," Cuomo said. The West Side Highway is currently closed from 14th Street to the tunnel, though the NYPD says it will likely be reopened tonight.

Both the NYPD and the FBI have asked New Yorkers with any information regarding yesterday's attack, or any future threat, to contact investigators through a number of hotlines, including 1-800-CALLFBI and online at fbi.gov/nyctribeca, where witnesses are encouraged to upload photos and videos from the scene.

Additional reporting by Gwynne Hogan.