West Ham manager Slaven Bilic was shocked at the attack on the Borussia Dortmund team coach, but fears such incidents are impossible to prevent.
Three explosions occurred around the bus - believed to be a targeted bomb attack - as the Dortmund players left the team hotel en route to the Signal Iduna Park stadium for the first leg of the Champions League quarter-final against Monaco, which was swiftly postponed.
Dortmund's Spanish defender Marc Bartra was taken to hospital, where he required an operation for a broken bone in his right wrist.
Bilic recalled a similarly frightening incident while he was managing Turkish side Besiktas, when rival club Fenerbahce's bus was shot at.
"I remember once when I was in Turkey when Fenerbahce were in Trabzon and the coach was attacked," he said.
"There was a shotgun and it just missed the driver, and they were driving at 80mph. It was so close.
"Those people are doing those kind of things because they don't want us to feel secure - not just footballers but you and me and the whole world. Nobody is secure.
"But you have to try to continue with your normal life. We sympathise with Dortmund, of course, and it was such a shock. You have to continue to do your job. You have to continue with your life.
"But I don't know, for example, how Dortmund could stop that attack. It's impossible. What one club can do to prevent it, I really don't know."
West Ham have suffered their own security scare this season, with striker Andy Carroll having been the victim of an attempted robbery at gunpoint in November as he drove home from training.