De Blasio: Arresting Suspect Will Confirm Whether Bombings Were 'Lone Wolf or Bigger'

New York Mayor Bill de Blasio said this morning that a suspect being sought by the FBI in connection with a Saturday night explosion in Chelsea must be caught before officials are "able to draw further conclusions" about the bombing.

The FBI issued a wanted poster for Ahmad Khan Rahami, 28, in connection with the bomb placed in a Dumpster outside 135 West 23rd Street that injured 29 people.

Rahami, a U.S. citizen born in Afghanistan, was last known to be living in Elizabeth, N.J., where a backpack containing up to five devices was discovered in a trash bin near a pub next to commuter train tracks. One of the devices went off when a robot was attempting to defuse it. "The robot that went in to disarm it, cut a wire and it exploded," Elizabeth Mayor Chris Bollwage said.

De Blasio said Rahami's description -- 5'6" tall, 200 pounds, brown hair and facial hair, considered armed and dangerous -- has been sent out to New Yorkers via the city's cell phone alert system.

Law enforcement officials told CNN that the Saturday morning New Jersey charity race bombing, the Manhattan bombing, a pressure-cooker device found a few blocks from the Chelsea attack, and the Elizabeth train tracks bombs leads them to believe a terror cell may be at work in the area.

De Blasio told MSNBC "we do not yet know if this was a lone wolf or if it was something involving additional individuals."

"This individual is the key, getting him in for questioning. I think that's going to tell us a lot as to whether it was a lone wolf or something bigger," the mayor said. "We have to assume, since we, again, believe there's the direct involvement in a bombing, we have to assume he would be well armed. In this city, of course, we have our police on alert. We have our critical response command, which is over 500 anti-terror officers, on alert. Very heavily armed and ready. A lot of police presence in New York City today, in part because of the United Nations General Assembly, but also to be preventative."

Speeches from world leaders begin Tuesday in the General Assembly.

A car was stopped by federal officials at the Verrazano Bridge on Sunday night, and the five occupants inside were taken into questioning. "Can't go into a lot of detail on that, but I can safely say that that stop of that vehicle was helpful and important," de Blasio said. "And a number of other efforts were made overnight to locate information. That's what allowed us to zero in on this individual."

"We're not at a conclusive point yet, but more and more indications suggest a connection between New York and New Jersey," the mayor added. "...But we don't draw conclusions until we have the evidence that we believe is accurate that then we can give to the public."