times sqaure
A member of the NYPD Joint Terrorism Task Force patrols in Times Square in the Manhattan borough in New York, March 22, 2016. Reuters/Stephanie Keith

UPDATE: 11:12 p.m. EDT -- The unidentified driver of a truck left unattended in Times Square on Saturday night was handcuffed and taken in for questioning by New York City police, WCBS-TV reported. Police began investigating after the truck's keys were seen in the ignition, with a gas container visible in the front and wires visible, the report said.

Security measures included clearing the block of 46th Street, where the truck was parked, and moving the audience of the Broadway show "Hamilton," playing nearby, to the basement of the theater until safety was assured, WCBS reported.

Original story:

Police in New York City temporarily shut down part of Times Square in Manhattan on Saturday night as they investigated a truck that had been left unattended, with its engine running, sparking security fears. Witnesses tweeted photos of police cordoning off large sections of the normally bustling entertainment and retail hub, with some Twitter users posting concerns about a possible bomb.

But just minutes after the reports surfaced, a New York Police Department spokesman said all was clear. J. Peter Donald, director of communications for the NYPD, posted to Twitter just after 8:30 p.m. EDT that the shutdown occurred because "a suspicious truck was left running and unattended."

Police began working to clear the area after discovering the truck around 8 p.m. -- with the bomb squad, fire department and paramedics all responding, WPIX-TV reported. The area around Seventh Avenue and 46th Street was entirely cleared, with NYPD officers telling tourists and others to leave, WCBS-TV reported.

CeFaan Kim, a reporter for WABC-TV in New York, posted to Twitter that counterterrorism officers had been called to the scene. Kim later posted a photo of what he reported was the inside of the truck.

On the heels of a spate of terrorist attacks — especially those organized by, or inspired by, the Islamic State group, also known as ISIS or ISIL — security is typically tight in the Times Square area, as well as other parts of the city, such as Grand Central Terminal and Penn Station.

Days after the Nov. 13 attacks in Paris that killed 130 people, ISIS posted a video that showed images of Times Square, among other New York locations, cut together with images of what appeared to be a man wearing an explosive device. The NYPD said at the time that it was aware of the video and would remain vigilant. A little more than one month later, some 6,000 NYPD officers were assigned to patrol Times Square on New Year's Eve 2015, an increase of 500 officers over 2014. Recently, fears of new attacks have been stoked by bombings in Brussels on March 22 that killed 22 people and injured scores more.