A woman drove onto the sidewalk on a busy part of the Last Vegas Strip to mow down pedestrians on Sunday night, police say.
One person was killed and at least 30 others were injured.
Sheriff Joe Lombardo, of the Las Vegas Metropolitan Police, said video showed Lakeisha Holloway intentionally drove her car onto the sidewalk to run over pedestrians.
Holloway, Lombardo said, was traveling with a three-year-old toddler in the car and she did not show signs of being drunk but a drug recognition expert believed that "she was under some sort of stimulus."
"The intentional act is going to be very hard to explain," Lombardo said. "I do not believe it to be an act of terrorism."
However, the sheriff said, terrorism has not been ruled out because they do not yet have a clear idea of Holloway's past.
"Bystander Justin Cochrane told the Review-Journal he witnessed an older, brown Oldsmobile plow into people, slow down and accelerate again.
"He said people were chasing the car, which he described as having a busted-out windshield. Cochrane said he saw the car 'crushing' people, including someone he described as a kid who looked about 10 years old.
"Rabia and Atif Qureshi, who also witnessed the crash, said the vehicle plowed into pedestrians, sending them flying like 'bowling pins.'"
Lombardo said that three people were critically injured and the three-year-old was now in protective custody. The Clark County Coroner identified the woman killed as 32-year-old Jessica Valenzuela of Buckeye, Ariz.
District Attorney Steven Wolfson said that Holloway will face charges including murder, child abuse and leaving the scene of an accident.