MANCHESTER, England (CBSNewYork/CBS News/AP) -- At least 22 people were killed and more than 50 injured after a suicide bomber blast at an Ariana Grande concert Monday night.
Greater Manchester police confirmed the deaths and injuries in the explosion just before 10:35 p.m. local time. Police said it was "currently being treated as a terrorist incident until police know otherwise."
Greater Manchester Police Chief Constable Ian Hopkins said the injured are being treated at six hospitals around Manchester.
"This is clearly a concerning time for people, but we are doing all we can working with local and national agencies to support those affected and gather information about what happened tonight," Hopkins said. "As you will understand, we are still receiving information and updates so will provide more details when we have a clear picture."
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.
A source said there were two explosions that contained nails.
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.
Many of the victims were young girls, the source told CBS News.
The source said that one person was detained in a vehicle, but it is not clear what if any involvement that potential suspect may have had in the attack.
The blasts sent people screaming and scrambling for the exits of the arena.
"There were bodies scattered about everywhere," said witness Kiera Dawber.
Ambulances rushed to the scene as terrified concertgoers frantically tried to get away.
"Massive bang and everyone started screaming and crying - trampling over us," another witness said. "It was awful."
"A huge bomb-like bang went off that hugely panicked everyone and we were all trying to flee the arena," concertgoer Majid Khan, 22, told Britain's Press Association. "It was one bang and essentially everyone from the other side of the arena where the bang was heard from suddenly came running towards us as they were trying to exit."
Added Oliver Jones, 17: "The bang echoed around the foyer of the arena and people started to run."
Joseph Carozza, a representative from Grande's U.S. record label, said the singer is OK and they are investigating what happened.
Hours after the concert, Grande tweeted she was "broken and sorry."
Following the attack, police advised the public to avoid the area around the Manchester Arena, and the train station near the arena, Victoria Station, was evacuated and all trains canceled.
"Due to an incident involving the emergency services [Manchester Victoria] has been evacuated," Northern train service officials said. "We will provide further updates when possible."
Video from inside the arena showed concertgoers screaming as they made their way out amid a sea of pink balloons.
The U.S. Embassy in London issued a statement Monday alerting U.S. citizens to "maintain security awareness" and seek guidance from local authorities.
"We strongly encourage U.S. citizens in the United Kingdom to directly contact concerned family members in the United States to advise them of your safety," the statement read.
U.K. Prime Minister Theresa May said in a statement that officials "are working to establish the full details of what is being treated by the police as an appalling terrorist attack."
"All our thoughts are with the victims and the families of those who have been affected," May said.
Jeremy Corbyn, leader of the Labour Party, responded to reports of the incident on Twitter.
"Terrible incident in Manchester," he said. "My thoughts are with all those affected and our brilliant emergency services."
Late Monday, Mayor Bill de Blasio 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."
Heavily-armed NYPD Hercules teams were also posted Monday night at Madison Square Garden – a reassuring sight for anyone rattled by the apparent terrorist attack across the Atlantic.
The Dangerous Woman Tour is the third concert tour by Grande and supports her third studio album, "Dangerous Woman."
Grande's role as Cat Valentine on Nickelodeon's high school sitcom "Victorious" propelled her to teen idol status, starting in 2010. The 23-year-old Grande, with her signature high ponytail, went on to also star in spinoffs that included "iCarly," as she worked to develop her recording career.
The tour began in Phoenix in February. After Manchester, Grande was to perform at venues in Europe, including Belgium, Poland, Germany, Switzerland and France, with concerts in Latin America and Asia to follow.
(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)
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