Saturday's explosion shook busy New York City's Chelsea neighborhood and sent panicked people scrambling for cover. Police continued to scour the area on Sunday for clues about who was responsible for the explosion and a motive.
A few blocks away from the blast site and shortly after the explosion occurred, investigators found one possible lead: a pressure cooker, with dark-colored wiring sticking out, connected by silver duct tape to what appears to be a cellphone, officials said.
The blast occurred on the same day an explosion went off near a Marine Corps charity run in New Jersey and a man stabbed nine people at a Minnesota mall, leaving many across the country on edge.
Authorities are investigating all three incidents as possible terror acts.
Investigators found similarities between the explosives used in both states, according to multiple law enforcement officials, but authorities said they have not concluded the incidents are linked.
In New York, law enforcement officials and the mayor said that without knowing who's responsible or what the motive was, it's too soon to call the Saturday bombing a terror attack.
Surveillance video shows a man dragging what appears to be a duffel bag with wheels near the site of the West 23rd street explosion about 40 minutes before the blast, according to multiple local and federal law enforcement sources.
About 10 minutes later, surveillance video shows the same man with what appears to be the same duffel bag on West 27th street, multiple law enforcement sources said.
In the video, the man leaves the duffel bag where police later found the unexploded pressure cooker.
After he leaves, the video shows two men removing a white garbage bag believed to contain the pressure cooker from the duffel bag and leave it on the sidewalk, according to a senior law enforcement official and another source familiar with the video.
Investigators have not determined if those two men are connected to the man with the duffel bag on both streets, the sources said.
The device was transported to the NYPD Bomb Squad facility at Rodman's Neck Range in the Bronx.
NYPD and FBI Bomb technicians rendered the device safe. A forensic examination of the device and its components will be conducted at the FBI Laboratory at Quantico, Virginia.
As investigators combed through surveillance video for clues, police officers and federal agents searched the streets with flashlights, robots and dogs early Sunday to ensure there were no other devices in the area.
Stepped-up security across the city is common as world leaders arrive for the United Nations General Assembly meeting, which is underway. But now it will be even more intense, de Blasio said.
New York Gov. Andrew Cuomo added that 1,000 additional New York State Police officers and National Guard troops will be deployed to patrol bus terminals, airports and subway stations.
The increased policing, Cuomo said, is "just to err on the side of caution."
"I want New Yorkers to be confident when they go back to work on Monday that New York is up and running and we're doing everything that we need to do," he said.
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