British authorities have arrested seven people this week after finding a cache of firearms and other weapons in the trunk of a car impounded earlier this week.

Police said they arrested three of the men Tuesday, three on Wednesday, and one on Thursday. The car had been stopped on a major highway earlier this week and impounded for not carrying insurance. The detainees are being held on suspicion of plotting terrorist attacks.

Police said the seven arrests are not connected to the Thursday arrest of six people who were also suspected of planning attacks. Authorities say neither group had plans to attack the upcoming Olympic Games, which begin in London later this month.

The terror alert in Britain is currently set at “substantial,” meaning there is a strong possibility of a terrorist attack as London prepares to host the Olympics. Security officials say they have no specific intelligence saying the Olympics will be targeted.