Seven people have been confirmed dead with 48 also injured, after a white van drove into pedestrians on London Bridge, before coming to a stop on Borough High Street, where three men exited the vehicle and began carrying out knife attacks.
The incident came less than two weeks after 22 people were killed when a bomb was detonated at an Ariana Grande concert at Manchester Arena.
The US singer, who is back in the UK to play a benefit gig for the victims of the Manchester attack on Sunday evening, was among the first to pay tribute, after news of the latest attack broke.
Taking to Twitter, she wrote:
Many other famous names shared their disbelief at the events, as well as sending their well wishes to those affected:
Three male attackers were shot by police, who say they believe all who carried out the attacks have been killed.
Members of the public who are concerned about friends and relatives should ring 0800 096 1233 or 020 7158 0197.