The Latest on the Ariana Grande Concert Bombing in Manchester

■ The police carried out a controlled explosion near the arena but later said the suspicious material was harmless. Bomb squads continued to comb through downtown Manchester.

‘Everyone Started Crying and Screaming’

Laura Bruce, 18, was with her sister Amy, 25, in one of the arena’s upper tiers when they heard the explosion. “Everyone below us just turned and ran,” she said. “Because we were higher up, we could not get out for five minutes. When we came out, a man walked past us just covered in blood.”

Sophie Tedd, 25, had traveled from Darlington to attend the concert with her friend, Jessica Holmes. At the end of the concert, they heard a loud bang and initially wondered whether “a speaker had blown.”

The Terrorism Threat in Britain

The Manchester police are working on the assumption that the deadly explosion at the concert was an act of terrorism. If so, it would be the worst act of terrorism in Britain since the 2005 bombings of London’s buses and subway killed 52 people.

But the British authorities, who have foiled numerous terrorist plots, will hardly be surprised. The threat level set by MI5, the domestic intelligence service, has been set at “severe,” the second-highest level, for months, meaning that an attack was considered “highly likely.” And counterterrorism officials have been warning that as the Islamic State comes under more military pressure in Iraq and Syria, it will try to strike abroad.

At one of the hospitals, the Manchester Royal Infirmary, anxious relatives, many in tears, showed up to check on their loved ones. Outside the pediatric emergency department, a van carrying blood supplies pulled in behind an ambulance.

The injured were being treated at six hospitals, said Chief Constable Ian Hopkins of the Greater Manchester Police. The police set up an emergency number — 0161 856 9400 — “for those who are concerned about loved ones or anyone who may have been in the area,” the chief constable said.

Nail Bomb Believed Used in Explosion

Witnesses said that the attack appeared to involve the use of a nail bomb. Nail bombs are used to magnify the destructive power of explosives, as the shrapnel increases the bomb’s ability to wound its victims. A nail bomb was believed to have been used Monday in an attack at a military hospital in Bangkok that wounded two dozen people.

Nail bombs use shrapnel like steel balls, razors, screws and other pieces of metal to enhance their destructive capacity. They were used in Britain by the Irish Republican Army in its campaign against the British government, including in a 1981 attack in central London that killed one women and injured 50 others.

Speculation that there might be another explosive device rose hours after the blast at deaths at the concert hall when the Manchester police said they had carried out “precautionary controlled explosion in Cathedral Garden.” It turned out to have been abandoned clothing, the police said, “not a suspicious item.”

— John Harney

Attack Came After ISIS Plea

Last week, the Islamic State released a 44-minute video featuring fighters of different nationalities, enjoining their supporters back home to carry out acts of violence. Among them was a man identified as a British national, according to a translation of the video provided by the Middle East Media Research Institute, which tracks jihadi propaganda.

A year earlier, Ms. Grande had released “The Way,” a debut single that would propel her nascent music career. The New York Times music critic Jon Caramanica later wrote that she transitioned from teen actress to pop diva through a “combination of exceptional voice, exceptional pluck and an exceptional sense of which hole in the marketplace she could exploit.”

— Mike Ives

U.S. Intelligence Briefed on Attack

Intelligence officials in the United States were briefed on the Manchester explosion late Monday and were told it appeared to be a terror attack, said one senior official who was not authorized to discuss the situation publicly and spoke on condition of anonymity.

British intelligence and counterterrorism officials said late Monday that they were “treating the incident as terrorism,” while investigating reports of a possible suicide bomber at the scene detonating an improvised bomb containing deadly shrapnel such as nuts and bolts.

— Adam Goldman and Eric Schmitt

Arena Largest Such Venue in Britain

The Manchester Arena is one of the world’s busiest areas, and the largest indoor venue in Britain with a capacity of 21,000, or 18,000 for concerts. It was constructed as part of Manchester’s bid to host the Olympic Games in 1996 and 2000, and is connected to the Manchester Victoria Station, which was closed because of the attack.

— Gerry Mullany

Rail Service at Busy Hub to Remain Suspended

Rail service at Manchester Victoria, a major transportation hub in the city, was suspended late Monday night and will remain closed on Tuesday. Manchester’s light rail service, Metrolink, has also been suspended at the station.

— Matthew Haag

Firm Describes Security at Arena

The Pennsylvania-based company SMG manages the Manchester Arena, and Wes Westley, the president and CEO of the company, described the precautions at the venue.

He explained that attendees arrive through a large public foyer, which is where the explosion occurred. The area, which connects to the Manchester Victoria rail station, is where parents often wait for their children after the concerts.

The incident “occurred in a public space outside of Manchester Arena,” the company said.

— Ben Sisario

♦ Culled from the NY Times