A woman was killed and 22 people injured when a car slammed into a crowd in New York's Times Square on Thursday, authorities said.

Police said the driver, Richard Rojas, was taken into custody and was being given a breathalyzer test. Photos from the scene showed multiple victims on the ground near the maroon Honda sedan, which came to rest on two wheels, wedged up against a light pole and metal barriers. It was not immediately clear what caused the crash.

"There is no indication that this was an act of terrorism," Mayor Bill de Blasio said. "That being said, we are reinforcing key locations around the city with our anti-terror units of NYPD."

De Blasio lauded the quick efforts of police, fire and emergency medical teams. But he added: "It's a tough day for New York City."

Rojas, 26, is a Bronx resident, U.S. citizen and Navy veteran, the mayor said. NYPD Commissioner Jame O'Neill said Rojas had two prior DUI arrests.

New York Fire Commissioner Daniel Nigro said four people were critically injured but were expected to survive. Police and fire officials closed off an area of several blocks.

White House spokesman Sean Spicer said President Trump was made aware of the incident.

Brooklyn resident Asa Lowe was standing outside the Levi's store enjoying the weather when he heard screaming. He turned around and saw the car hitting people on the sidewalk.

He says the driver was "just mowing down people. He didn't stop."

The car hit a barricade and stopped. Lowe says the driver then got out of his car and started running until people tackled him. Lowe saw injured people, including a woman who "had tracks all over her body."

Tourists Patrick and Kelly Graves of Sheboygan, Wisconsin, were waiting to get on a tour bus when they heard the crash.

Kelly Graves said she feared the worst, maybe a bomb, as "chaos" erupted and people began running. People rushed to help the injured, who were lying on the sidewalk.

The sidewalks in many parts of Times Square and surrounding blocks are lined with metal posts designed to prevent cars from getting onto the sidewalks and other public areas.

That network of barricades, though, is far from a complete defense. There are many areas where vehicles could be driven onto packed sidewalks or public plazas.

Times Square also has a heavy police presence at all hours of the day and night.