"To be honest, there is a little concern," Wright said, per Chris Tomasson of the Pioneer Press. "You never know what can happen. I feel (terrorists) always look for big events. ... We still have a little while before the game, but it's always a concern in the back of my head."
Thielen said he expects London police and the NFL to provide a "different level of security" for the Vikings' game against the Cleveland Browns. The two teams are scheduled to play in London on Oct. 29.
"It's obviously terrible," Thielen said. "My heart goes out of those people affected by that. Obviously, we're all affected by it. It's tough to see that around the world. It doesn't matter where it is. ... The scary part is you just never know."
England has seen three terror attacks hit the country since March, killing tens of people and wounding hundreds. Two of the attacks have taken place in London and one in Manchester, the latter at a concert event for singer Ariana Grande.
The event level of the NFL's trips to London is generally similar to that of a major concert. The Vikings-Browns game is the last of four in London next season.
"All of those impacted by the tragic events in London are in our thoughts and prayers," NFL spokesman Michael Signora said in a statement. "...We will continue to work in close coordination with our teams, our security staffs, outside specialists, and law enforcement and intelligence personnel in both countries to ensure the safety of our events this fall."
Cornerback Terence Newman and defensive end Brian Robison said Tuesday that they have no concern about playing in London next season.