The US Navy veteran charged with murder after plowing a car into pedestrians in Times Square suffers from mental health problems and intentionally lashed out, New York's mayor said Friday.
Thursday's incident sparked fear in the US financial capital after deadly car rammings in London, Berlin and the French city of Nice, but authorities said there was no evidence the crash was terror-related.
An 18-year-old woman from Michigan was killed and 22 other people injured, including the woman's 13-year-old sister. The sister remains in a critical condition and a Canadian citizen was seriously injured, officials said.
Richard Rojas, 26, a former Navy electrician from the Bronx, was arrested at the scene and charged with one count of murder in the death of an 18-year-old tourist and with 20 counts of attempted murder.
"What we know right now continues to confirm it was not an act of terror," Mayor Bill de Blasio told WNYC public radio on Friday.
Rojas "had demonstrated mental health issues going back to childhood," he added.
"He was troubled and lashing out," the mayor said. "At the root of this, from what we know so far, is an untreated mental health issue going back probably decades."
Toxicology tests are yet to determine whether drugs in his system played a role in his behavior.
"We don't know the full analysis and whether the type of drugs in his system exacerbated his feelings in a negative way," the mayor told WNYC.
De Blasio, a progressive Democrat seeking re-election this year, said authorities would assess whether they needed to step up security to stop similar incidents from happening in the future.
Police patrols in Times Square, one of the world's busiest districts, were already beefed up in recent years, following a 2010 car bombing attempt.
Police also bolstered security for public gatherings in the wake of attacks in Europe.
"We don't allow vehicles to cross the path of... parades anymore, and we put barrier trucks, sand trucks, in the way," de Blasio said.
Shortly before noon on Thursday, Rojas's Honda Accord mounted the sidewalk at high speed, bowling over pedestrians and sending others fleeing in fright for three blocks in Times Square -- one of the world's busiest districts -- police said.
Rojas was arrested for drunk driving in 2008 and 2015, and detained earlier this month on charges of menacing behavior, police said.
News reports also drew a portrait of a troubled young man who seemed changed when he returned home in 2014 from a three-year stint in the US Navy.
During his arrest, Rojas allegedly told police: "You were supposed to shoot me! I wanted to kill them," New York newspapers reported.
He also said that he "hears voices."
Protective bollards -- short, sturdy posts to prevent vehicles from driving onto sidewalks -- were installed in Times Square last year, just in time for the New Year's Eve celebration that regularly brings a million or more people to the area.