NEW YORK (CBSNewYork/AP) -- Mayor Bill de Blasio said the NYPD was closely monitoring the situation Monday night, after 22 people were killed in an explosion at an Ariana Grande concert in Manchester, England.
Security has been tightened at several sites across New York City and New York state.
The explosion at the Manchester Arena killed 19 people -- largely teenage girls -- and left about 50 people injured, Greater Manchester Police said. Officials said it was "currently being treated as a terrorist incident until police know otherwise."
Two U.S. law enforcement told CBS News the blast was carried out by a suicide bomber. The sources said the bomber traveled by tube, or subway, to the train station near the arena –Victoria Station – and went to the ticket area. There, he detonated the device as people were leaving the concert, the sources said.
Sources said ball bearings have been recovered, and officials are tracing the movements of the attacker through closed-circuit television.
Parts of the suicide bomber have been recovered, a source said.
The mayor said in a tweet: "Our prayers are with the victims, their families, and the first responders in Manchester. The NYPD is closely monitoring the situation."
The NYPD Counterterrorism Unit also tweeted it was closely monitoring developments.
Gov. Andrew Cuomo also issued a tweet, saying state police will also step up patrols and security.
"This apparent act of terrorism, targeting a concert attended by thousands of teenagers and young people, is an inexplicable and abhorrent assault on our universal values as human beings," Cuomo said in a statement. "An attack on one is an attack on all, and New York stands in solidarity with the British people and our friends around the world against the forces of hate and terror."
Cuomo said security will be increased at airports, bridges, tunnels and mass transit systems.
"The safety of New Yorkers is priority number one, and we are in close contact with federal and local officials as we continue to remain vigilant in the wake of this tragedy," he said in the statement."
As CBS2's Tony Aiello reported, heavily-armed NYPD Hercules teams were posted Monday night at Madison Square Garden – a reassuring sight for anyone rattled by the apparent terrorist attack across the Atlantic.
"Madison Square Garden has increased security measures, including a greater police presence, and is continuing to work closely with local law enforcement to ensure we remain informed of any potential concerns," MSG said in a statement.
The NYPD also stepped up security at Third Avenue and 51st Street, outside the building that houses the British Consulate.
CBS News Senior Investigative Producer Pat Milton told CBSN what the NYPD and other U.S. police departments might be on the watch for.
"It would put everyone on a higher state of alert. They would be looking at concerts and arenas in New York. New York has always been a prime interest and target of terrorists," Milton said. "The NYPD does have liaisons that are actually stationed in Britain, and the same with the FBI – they've got people. They've got FBI liaisons that are actually in the embassy there."
Security expert Manny Gomez told CBS2's Aiello the NYPD and FBI are always on top of things after an overseas attack.
"NYPD and the New York office of the FBI is very proactive," Gomez said. "The NYPD usually sends out detectives and crime scene investigator when they have an outside attack like this -- what happened, and how we could learn from it to prevent similar attacks here in New York City?"
At big events, bag checks and sometimes metal detectors have become a fact of life.
Gomez said what we are learning about this particular attack in England is likely to prompt even more security initiatives in New York.
"The takeaway is from this particular attack is that the attack happened outside the venue in a public area that didn't require any security screening," Gomez said, "and thus, just like we have vendors, et cetera, outside of Madison Square Garden; outside of other public arenas, I think we're going to take another measure and an outside ring of security to counteract that possibility of a copycat here in New York City."
The NYPD told CBS2 late Monday night that the department has been in contact with English authorities and monitoring the situation in Manchester "to inform our operations and deployments in New York City."
The NYPD said out of an abundance of caution, it has moved additional heavy weapon teams to high-profile locations around the city. People are likely to see those team, as well as officers with vapor wake dogs in the days ahead.
Grande last played Madison Square Garden in February. No doubt, the 52,000 people who attended the two shows were thinking back on the experience Monday night.
The next major event at Madison Square Garden is a Billy Joel concert on Thursday. MSG said it is working with the NYPD to come up with appropriate security.
(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)
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