The first major marathon to take place after the bombings at the Boston Marathon began with 30 seconds of silence on Sunday, CNN reports.
The moment of silence was just one of the many tributes to the victims of Monday's Boston bombings. Many of the 36,000 runners wore black ribbons or shirts that said "Boston" on them, and race organizers said they plan on donating $3 to The One Fund Boston for each runner who crosses the finish line.
The London Marathon draws thousands of spectators in addition to the runners, and race organizers increased the amount of security as an added safety precaution after Monday's attack, CBS reports. Police added 40 percent more officers and surveillance to ensure the safety of race participants and spectators, but authorities said that canceling the race was never an option.
Some of the racers participating had previously run in the Boston marathon, and said they wanted to run as a memorial. "It is terrible what happened in Boston, but we can't look back, we must look forward," said racer Tomasz Hamerlak, who competed in both races. "The show must go on."