Authorities investigating an attempted terror attack in New York have said the would-be suicide bomber detonated a homemade bomb attached to his body.
The suspect, identified as 27-year-old, Akayed Ullah, was taken to hospital with wounds from the blast and three people nearby were injured.
Bill de Blasio, the mayor of New York, described the rush-hour blast as an “attempted terror attack”, adding: “Thank God the perpetrator did not achieve his ultimate goals.”
Officials said the explosion was reported at 7.20am (12.20pm GMT) in a below-ground walkway connecting subway lines near Times Square.
Emergency services found Ullah at the scene with burns and lacerations to his hands and abdomen.
Police believe Ullah detonated the device himself but could not confirm whether the crowded walkway itself was the target, or whether the suspect may have been travelling towards somewhere else.
He was arrested and taken to hospital for treatment in the custody of police. Three people standing nearby at the time of the blast presented themselves to two nearby hospitals with minor injuries including ringing in the ears and headaches.
Several New York subway lines were evacuated and parts of the network temporarily shut down, before being gradually reopened.
What was the device?
The Governor of New York, Andrew Cuomo, described the device as “effectively low-tech”, adding: “Anyone can go on the internet and download garbage and vile-ness on how to put together an amateur level explosive device and that is the reality that we live in.”
John Miller, deputy commissioner of the NYPD, told a press conference the device was “based on a pipe bomb”.
“It was affixed to his person with a combination of Velcro and zip ties. Bomb technicians processing crime scene,” he told a press conference, adding that experts were analysing the device to confirm what explosive it contained and how it was constructed.
Pipe bombs are a type of improvised device that see a sealed section of pipe filled with explosive material, aiming to increase the power of an explosion because of increased pressure and shrapnel.
It is unusual for a single pipe bomb, which are normally concealed or used as part of larger devices, to be attached to a person.
Suicide vests can be made from several pipe bombs or another combination of explosives packed with ball bearings or shrapnel.
Who is responsible?
No terrorist group immediately issued a claim of responsibility and officials have not confirmed any links or sympathies by the bomber.
Mr De Blasio said only Ullah was believed to be involved and there were no further known threats to New York, adding: “At this point in time all we know is one individual who was unsuccessful in his aims.”
Mr O’Neill said that officers were investigating whether the bomber shouted anything before detonating his device.
When asked if he was connected to Isis, he replied: “He did make statements but we’re not going to talk about that right now.”
Is Isis involved?
The terrorist group did not immediately claim responsibility for the bombing but statements have been issued hours or even days after incidents in the past.
Isis does not always link itself to attack that are unsuccessful or where the suspect has been arrested.
A recent anomaly was the Parsons Green attack, which saw a homemade bomb partially explode on the London Underground.
A teenage Iraqi refugee was arrested on suspicion of attempting the attack, which saw several people injured by a device concealed inside a Lidl bag and detonated during the morning rush-hour in September.
Isis has been intensifying its calls for supporters to carry out terror attacks around the world as it becomes harder for jihadis to travel to its dwindling territories in Iraq and Syria.
The group has issued several rounds of detailed guidance on carrying out massacres using cars, lorries, knives and bombs.
A signature of Isis bombings has been the powerful and volatile explosive TATP, which was used in attacks including Paris and Brussels, but was not immediately evident in New York.
Al-Qaeda has also issued bomb-making instructions to supporters, with one notorious article on making a pipe bomb issued in an English-language propaganda magazine being that has been tied to atrocities including the Boston bombing.
Have there been other terror attacks in New York recently?
Isis claimed responsibility for a terror attack that left eight people dead in Manhattan on 31 October.
Investigators confirmed Sayfullo Saipov was inspired by the group’s propaganda to launch a rampage using a truck, after he allegedly declared his intentions to officials and asked to hang an Isis flag in his hospital room.
The NYPD said he had followed Isis instructions “almost to a T” but no formal links to the group had been uncovered.
In September 2016, three pressure cooker bombs exploded in New York and New Jersey as part of a coordinated plot by an Islamist inspired by both al-Qaeda and Isis.
Ahmad Khan Rahimi is alleged to have planted several other bombs that did not detonate.
A blood-soaked journal found on the suspect after he was shot and detained by police contained references to Isis’ late spokesman, Abu Muhammad al-Adnani, and a speech calling on supporters to “attack the kuffar [disbelievers] in their backyard”.
The journal also expressed admiration for “brother Osama bin Laden” and Anwar al-Awlaki, the American-Yemeni al-Qaeda recruiter killed in a US drone strike in 2011.
It read: “I looked for guidance and Alhumdulilah [praise God], guidance came Sheikh Anwar [al-Awlaki], Brother Adnani/Dawla [Isis].”
Mr Miller said that around 26 terror plots have been foiled in New York since al-Qaeda’s 9/11 attacks, including the 2010 Times Square car bombing attempt, which was linked to the Pakistani Taliban.
He added: “We have prevented a significant number of attacks but this is a fact of life whether you’re in New York or London, or Paris. The question is ‘can it happen here?’ And the answer is it can happen anywhere.”
Are transport networks being targeted?
The bombing is the latest incident to target transport networks, which have been a recurring location of terror attacks around the world.
Trains and underground networks have been the site of atrocities by groups including Isis, al-Qaeda, other Islamists, the IRA, neo-fascists and Sikh militants.
Among the deadliest attack of its kind is the 2006 Mumbai train bombings, which saw seven blasts in 11 minutes kill more than 200 people on the Indian city’s suburban railway.
The Madrid train bombings in 2004 killed 192 victims in 10 near-simultaneous explosions in the morning rush hour, while the 2008 Mumbai attackers also included a railway station among targets.
Bombs were detonated on both the London Underground and a bus in the 2005 London bombings, which killed 52 victims, and were followed two weeks later by four more attempted attacks on public transport.
Experts have ranked transport networks and interchanges among other “soft targets” that will continue to be used by terrorists searching for densely crowded sites with low security.