The New York Police Department posted on its Twitter feed that one person was in custody.
At least six people were killed and 15 were injured when a truck driver deliberately mowed down people in lower Manhattan Tuesday afternoon in what authorities are investigating as an act of terror, officials tell News 4 NY. O'Neill said the suspect "did make a statement" after the crash, which led police to declare the incident an act of terrorism.
White House spokeswoman Sarah Huckabee Sanders said president Donald Trump had been briefed by White House chief of staff John Kelly and "will be continually updated as more details are known".
Facebook activated its "safety check" feature following the deadly Halloween incident. The two-lane path is separated by a low median from West Street, part of the West Side Highway. Video from the scene showed large numbers of officers and police vehicles.
Witnesses reported hearing gun fire but it now appears that was from responding officers, who opened fire on the attacker. The truck was adorned with logos of the Home Depot hardware store chain.More news: White House: We Have Nothing to Do With Manafort's Indictment
"I heard four to six gunshots - everybody starts running", she added. Thoughts & prayers as we monitor the situation.
"What I saw was that the driver - he didn't look like he was bleeding", said Ramon Cruz, a witness. The guy with the two guns, for some reason, was running around.
"It was a white pickup truck". I didn't see him hit anybody.
Authorities did not immediately elaborate on what was happening, saying only that there was "police activity" and an ongoing investigation occurring around the intersection of West and Chambers streets in Lower Manhattan.