NEW YORK (CBSNewYork) — Investigators aren’t ruling out terrorism as the motive behind the bombing in Chelsea on Saturday night that injured 29 people.

Security is tight in the neighborhood and in areas around New York City that could be vulnerable to a terrorist attack.

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CBS2’s Steve Langford reported the perpetrators behind the explosion on West 23rd Street and the second pressure cooker device on West 27th Street succeeded in getting the city’s attention.

CHELSEA EXPLOSION: ‘Intentional’ Blast On W. 23rd Street; 29 Hurt | Sources: 2nd Device On W. 27th Pressure Cooker | Mayor: No Specific, Credible Threat To NYC 

“I am concerned,” NYPD Commissioner James O’Neill said. “We did have a bomb that was detonated on 23rd Street and we have no one apprehended, so of course I’m concerned.”

The inevitable downside for the party or parties responsible for this violence is that all the attention is not going to end well for them.

“You will see a very substantial NYPD presence this week, bigger than ever,” Mayor Bill de Blasio said.

While a joint task force of local, state and federal law enforcement agencies hunt down leads and suspects, NYPD personnel will be seen on the streets of the city, including heavy weapons teams on guard around town, along with heightened transit city.

“We’ll be doing enhanced bag checks throughout the city, not just in the major hubs, but we pick random stations throughout the city,” NYPD Chief of Department Carlos Gomez said.

Manny Gomez, corporate security expert and former FBI special agent, said the suspect or suspects in the Chelsea bombing and Seaside Park, New Jersey, explosion may be amateurs, but so far they’re still free.

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“We don’t have the resources to keep track of everybody that’s out there and a potential attacker, this is like trying to empty the ocean onto the beach,” Gomez said.

He continued, “Now we’re at a level of alert that this city has never seen since 9/11.”

NYPD sources said authorities have found an image in surveillance video showing a man “dropping” something near a dumpster prior to the blast in Chelsea that injured over two dozen people.

NYPD sources told CBS2 the person has not been identified, but they want to talk to him and others seen on video as potential witnesses in the area prior to the blast on West 23rd Street.

Police also have images from the second scene where a pressure cooker device failed to detonate on West 27th Street. Sources told CBS2 there are images of a man carrying what appears to be some type of case. They are looking to identify that individual as a potential witness and stopped short of calling him a suspect.

Police are using facial recognition software linked to criminal mug shot databases to try and identify.

NYPD sources also told CBS2 it is too early to tell if the devices are connected, despite reports linking the bombings in New York City and Seaside Park, New Jersey.

Sources said that there is no video or forensic evidence to support the theory that the same person was responsible for the bombing in Chelsea on Saturday night that injured 29 people and the pipe bombs in Seaside Park, New Jersey.

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However, they have not ruled out a possible connection as both devices used cellphones as detonators, but that is common in explosive devices.