Memorials are set to be held throughout the day on the 20th anniversary of the July 7th bombings in 2005.
52 people were killed and hundreds injured. Three devices were detonated on Underground trains at Aldgate, Edgware Road and Russell Square, while a fourth exploded on a double-decker bus in Tavistock Square.
Memorial services are taking place throughout the day with the prime minister, Mayor of London and Duchess of Edinburgh attending a memorial at St Paul's Cathedral.
A minute's silence was held at 8:49 at three London Underground stations marking the moment the tube attacks took place. A minute's silence was also held at Tavistock Square an hour later, attended by Keir Starmer.
Prime Minister Sir Keir Starmer and Mayor of London Sadiq Khan also attended a wreath laying ceremony at Hyde Park.
Starmer said: "Today the whole country will unite to remember the lives lost in the 7/7 attacks, and all those whose lives were changed forever.
"We honour the courage shown that day—the bravery of the emergency services, the strength of survivors, and the unity of Londoners in the face of terror.
"Those who tried to divide us failed. We stood together then, and we stand together now—against hate and for the values that define us of freedom, democracy and the rule of law."
The Tavistock Square bomb exploded outside the headquarters of the British Medical Association, where a conference was taking place. Doctors who treated the injured in the courtyard of BMA House have attended the memorial at St Paul's Cathedral.
BMA council chair Tom Dolphin said: "I was working in A&E at the Royal London that day and amidst the bustle and busyness of what was happening I was very conscious that people I knew were right there in BMA House in the thick of it. I was worried for them but also incredibly proud.
"Everybody who was at BMA House on that day remembers it very clearly as a day that changed everybody’s lives. I don’t think anybody goes through a day like that without coming out as a different person.
"I have a strong sense of pride that the doctors who were here, even those for whom emergency care is not their usual practice, were able to step up and provide support, care and comfort for the victims. They did that in a hugely traumatic situation that came out of nowhere – with no warning – and that’s something we can be very proud of as a profession and as their colleagues and friends.
"People go into medicine wanting to care for patients. That’s what motivates all of us. And that really showed up in those moments in the strongest possible way."
Staff from NHS Blood and Transplant have also paid tribute to those who were killed and praised NHS staff and blood and tissue donors who helped save lives that day.
30 minutes after the first attacks, blood donation staff started receiving emergency requests from hospital. Over the next 8 hours, 18 blue light deliveries were made to nine London hospitals. In total, 1,455 units of blood products were ordered by hospitals, and all were delivered. 25 patients required life-saving blood transfusions.
Andy Perry was working as a day shift supervisor on the day, He said: "What started out as just another normal day, quickly turned into a day you could never forget when just after 9am we started to hear reports that something had happened on the Tube but details were limited.
"Then the first phone call came through from a hospital to declare a major incident and a stream of others followed. We worked solidly throughout the day turning around the emergency orders for more blood coming in - while still processing all our usual daily deliveries.
"It was a surreal day, but everyone pulled together. As quickly as the delivery vehicles returned, we were re-loading and sending them back out again. By the end of the day we were all exhausted but also so proud of what had been achieved.
"That night I went home and just hugged my wife, thinking how many people would not have that privilege. Even after 20 years, the memories - and mix of emotions - about that day, still stay with me so vividly."
