Seven people have died after a terrorist attack at London Bridge and Borough Market. Here is what we know so far…

At least 22 people, including children, have been killed and 59 injured in a suicide bombing at a crowded pop concert in Manchester, the most deadly attack in Britain in a decade.

The horror unfolded at about 10.30pm on Monday at the end of a concert by the American singer Ariana Grande, whose music is popular with children and teenagers.

The attack, which took place in the foyer, caused hundreds of people to flee in terror, with young people at the concert separated from their parents in the chaos. It left a scene of carnage inside the concert venue, where medics described treating wounds consistent with shrapnel injury.

One witness said he could see nuts and bolts strewn on the floor of the foyer after the attack, which suggests a nail bomb may have been involved. Families of those injured later said nuts and bolts were removed in life-saving surgeries.

The attack came less than three weeks before Britain’s general election on 8 June and on the anniversary of the murder of Fusilier Lee Rigby. In response, all parties have suspended campaigning. Flags outside Downing Street flew at half-mast.

The prime minister chaired an emergency meeting of the government’s crisis committee, Cobra, on Tuesday morning and later travelled to Manchester to meet with local law enforcement and survivors. She was scheduled to chair a second Cobra meeting on Tuesday afternoon.

The home secretary, Amber Rudd, paid tribute to emergency services, saying: “This was a barbaric attack, deliberately targeting some of the most vulnerable in our society – young people and children out at a pop concert. My thoughts and prayers go out to the families and victims who have been affected.”

Greater Manchester police have confirmed that they believe the bombing was the responsibility of one man armed with an improvised explosive device. The man, named as 22-year-old Salman Abedi, is among the dead.

Police raided a number of properties in south Manchester in the wake of the attack, including one address in Fallowfield where a controlled explosion was used to gain entry.

The chief constable, Ian Hopkins, said: “We have been treating this as a terrorist incident and we believe that while the attack last night was conducted by one man, the priority is to establish whether he was acting alone or as part of a network.”

The investigation into the attack involves the police counter-terrorism network and Britain’s domestic security service, MI5.

The death toll would make it the worst event of its kind in Britain since the 7/7 bombing in 2005, which hit London’s transport network, killing 52 people.

Witnesses in Manchester described how, after the concert had finished, the house lights came up and then a loud bang was heard. Majid Khan, 22, said: “A huge bomb-like bang went off that hugely panicked everyone and we were all trying to flee the arena.

“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.”

Oliver Jones, 17, who attended with his 19-year-old sister, said: “The bang echoed around the foyer of the arena and people started to run.”

People outside the concert hall were visibly upset as a cacophony of sirens was heard and police and ambulance vehicles arrived at the scene.

Erin McDougle, 20, from Newcastle, said: “There was a loud bang at the end of the concert. The lights were already on so we knew it wasn’t part of the show. At first we thought it was a bomb. There was a lot of smoke. People started running out. When we got outside the arena there were dozens of police vans and quite a few ambulances.”

A group of young men from Sheffield said they had seen at least five people covered in blood and others being carried out by bouncers.

A mother, at the concert with her two daughters, described seeing a man she believes to have been the suicide bomber. Emma Johnson told BBC Radio 5 Live: “I turned and saw [a] bright red top in the crowd with a grey panel down the front with risen bits all over it. It was that which stood out because it was so intense among the crowds of people. As quick as I saw it the explosion happened.”

She said she was 15ft (4.5 metres) away. “It happened near where they sell the merchandise,” said Johnson. “There were dead bodies everywhere. I saw the remains of the torso and the remains of the body.”

Charlotte Campbell said she last heard from her 15-year-old daughter Olivia at 8.30pm on Monday, shortly before Grande went on stage, and was frantically trying to find her.

“Her dad is actually in Manchester looking for her,” she told BBC Radio 4’s Today programme. “I’ve got friends out looking for her, I’ve got people I don’t even know out looking for her.

“I’ve got people messaging me saying: ‘Look, we’ve got her photo and we’re out looking for her – we’ll get in contact with you if we see her’. I’m just hearing nothing – her phone’s dead.”

View image on Twitter

People in Manchester rallied round to help people caught up in the attack. Sikh temples and hotels offered refuge and some locals opened up their homes. Some taxi drivers waived their fares.

The attack happened despite years of warnings and tightening of security, especially around crowded paces. Investigators will want to find out the reason for the attack, where the material for the suspected device was bought and how it was designed.

Since the attack on London in 2005, measures have been put in place to restrict the purchase of materials that can be used to make homemade explosives.

The Manchester attack came after weeks of heightened activity and disrupted plots by police and MI5. In March, four people and the attacker died after an attack in Westminster, central London, which targeted the Houses of Parliament.

The terrorist threat level for Britain is at severe, meaning an attack is highly likely. The government is not planning to increase the threat level to critical. However, security is expected to be reviewed for major venues in Britain and elsewhere. London’s mayor, Sadiq Khan, said there would be more police on the streets of the capital on Tuesday after the “barbaric and sickening attack”.

The Metropolitan police commissioner, Cressida Dick, said the extra presence, including armed officers, would continue for as long as needed. She also said the force was working with all those planning events this weekend to ensure all necessary steps had been taken. Security was also stepped up in Scotland, where the chief constable deployed armed police on high visibility patrols in crowded areas, airports and railway stations.

In the US, the Department of Homeland Security warned of extra security measures.

World leaders expressed solidarity with the UK in the fight against terrorists. Donald Trump expressed his “deepest condolences” to the victims, condemning the attackers as “evil losers”. The French president, Emmanuel Macron, offered the British people “all the compassion and care of France which is at their side in mourning, with a particular thought for the victims and their families”. The German chancellor, Angela Merkel, on Monday expressed her “sorrow and horror”.

In a statement just before 3am, Hopkins said the police had received reports of an explosion at 10.33pm at the conclusion of the Ariana Grande concert.

He said: “This is clearly a very concerning time for everyone. We are doing all that we can, working with local and national agencies to support those affected as we gather information about what happened last night.”

Hopkins urged people to remain vigilant and to stay away from the area of the attack so emergency services could continue their work.