The family of an American slain in last week's attack in London expressed gratitude Monday for the kindness of strangers as they insisted some good would come from the tragedy. Kurt W. Cochran from Utah was on the last day of a European trip celebrating his 25th wedding anniversary when he was killed when an attacker mowed down pedestrians on Westminster Bridge before stabbing a police officer in a Parliament courtyard. Cochran's wife, Melissa, suffered a broken leg and rib and a cut head, but is steadily improving. 'So many people have been so kind, and we are deeply touched by their goodness and generosity,' said Melissa Cochran's brother, Clint Payne. 'Your notes, prayers, donations and love have helped us so much.' Attacker Khalid Masood was shot dead by police after his deadly rampage, which police have revealed lasted just 82 seconds. Police believe Masood — a 52-year-old Briton with convictions for violence who had spent several years in Saudi Arabia — acted alone, but are trying to determine whether others helped inspire or direct his actions. Detectives on Monday continued to question a 30-year-old man arrested Sunday and a 58-year-old man arrested shortly after Wednesday's attack. Both were detained in the central England city of Birmingham, where Masood had recently lived. Meanwhile, the British government repeated calls for tech companies to give police and intelligence services access to encrypted messages exchanged by terrorism suspects. Masood used the messaging service WhatsApp just before he went on his deadly rampage. Home Secretary Amber Rudd said Sunday that such services must not 'provide a secret place for terrorists to communicate with each other.' Tech companies have strongly resisted previous calls to create back-doors into encrypted messaging, arguing that to do so would compromise the secure communications underpinning everything from shopping to tax returns to online banking. Rudd is due to hold a previously scheduled meeting with internet companies on Thursday. Prime Minister Theresa May's spokesman, James Slack, said tech firms 'should be helping us more' to prevent terrorism. 'The ball is now in their court,' he said. Slack said that if agreement was not reached with the companies, the government 'rules nothing out,' including legislation.