With no international terrorist group claiming responsibility for a powerful explosion in Manhattan that left dozens wounded, the authorities on Sunday were combing through surveillance videos, interviewing eyewitnesses and sifting through remnants of the bomb itself for clues into the attack.
Even as the last of the victims was released from the hospital, the New York Police Department, joined by the Federal Bureau of Investigation, mounted a large-scale hunt for the person or people behind the attack. Officials said they did not know of any motive — political or social.
The hunt for the culprit took on added urgency as leaders from around the world make their way to the city for the annual United Nation’s General Assembly this week.
Gov. Andrew M. Cuomo said the powerful explosion that rocked the Chelsea neighborhood on Saturday night, injuring 29 people, did not appear to be linked to international terrorism, but that it was a powerful bomb designed to kill.
“This is one of the nightmare scenarios,” he said at a news conference on Sunday. “We really were very lucky that there were no fatalities.”
Four blocks away from the blast site, the authorities found and removed what they described as a second device. Mr. Cuomo said the devices appeared to be similar in design and one federal law enforcement official who agreed to speak about the continuing investigation only on condition of anonymity described it as a “viable device” that failed to detonate.
The authorities were also looking into whether the New York explosion was connected to a blast that happened 11 hours earlier when an improvised device exploded in a garbage can near the course of a charity race that was about to start in a small town on the Jersey Shore. That device went off around 9:30 a.m. near the boardwalk in Seaside Park, N.J., according to the Ocean County sheriff, Michael G. Mastronardy. No one was injured. The race, the Seaside Semper Five, a five-kilometer run and charity event along the waterfront that raises money for members of the United States Marine Corps and their families, was canceled.