Last Friday night, what was meant to be a gripping soccer match between France and Germany turned into a nightmare.
Two suicide bombers detonated their vests outside stadium entrances, with a third blowing himself up near the stadium. One innocent passer-by was killed.
The explosions, audible in the stadium as the game was played out, resulted in the evacuation of President Francois Hollande from the arena. An organized pitch invasion by fans after the game was also carried out.
The attacks at the Stade de France marked the beginning of a co-ordinated assault by terrorists on the city. When it was over, 130 people had been killed.
One week on, the question of whether security at sporting events will change for good is a pertinent one.
"People are on edge so… the standards for canceling an event or for changing an event venue are going to just be lower, and we just have to accept that, at least for the short term," Juliette Kayyem, a member of the International Center for Sport Security's advisory board and a former assistant secretary for intergovernmental affairs at the Department of Homeland Security, told CNBC in a phone interview.
This week saw two high profile international soccer friendlies – between Belgium and Spain, and Germany and the Netherlands – both cancelled amid security concerns.
The latter saw the stadium in Hannover evacuated after the city's president of police told local media that authorities had received "specific indications that an attack with explosives was planned."
In London, England's match against France was marked by the conspicuous presence of heavily armed police.
How then, will security around sporting events change? Kayyem said that spectators will see a "larger police presence in terms of uniformed police, there's no question in my mind that that will be the first thing."
Kayyem added that, "it may be that some places put in metal detectors where there were none before, rules or reiterating (of) rules about bags and bag checks."
In the wake of last week's events it is clear that sporting organizations, franchises and leagues are looking to reassure fans.
A day after the attacks, the NFL released a statement in which it said that it was "closely monitoring events" and had, "been in communication with the Department of Homeland Security and the FBI, which have informed us that there are no known threats against NFL stadiums."
On Thursday, soccer's English Premier League released a statement which said that it had been in consultation with its police and security advisors, as well as the U.K.'s Home Office, "in relation to the safety and security issues at matches in light of the terrorist attacks in Paris last Friday."
For Kayyem, stadium security should be seen as "layered", comprising everything from the design of an arena to crowd control operations, entries and exits and evacuation routes, even generators and back-up generators in case lights go out.
"But there is no way to have a perfectly secure sporting event, period. And anyone who says so is not telling the truth," she went on to add, before praising the "brilliance of the staggered evacuation" that took place at the Stade de France.
"People lose their heads when things like this happen and the French did not, they… understood what was going on," she said.
Going forward, are more stringent measures set to become the norm?
"We won't always be in this time," Kayyem said. "The British certainly know that all vulnerabilities ebb and flow, and the security apparatus will as well," she added.
"But over the short term, just given what happened in Paris, the sense of unease that people are feeling… will be reflected in more visible armed security."
By Anmar Frangoul, Special to CNBC.com. Follow him on Twitter @AnmarFrangoul.