Italian police have raided an alleged terrorist cell in Venice today, arresting three men and a young woman who were planning to travel to Syria.

The suspects were detained in the heart of historic Venice, in a series of raids conducted by police in the early morning.

All four of the suspects are from Kosovo, but hold Italian residence permits. After conducting surveillance on the group, police launched the raids after references to last week’s attack in London were made. In that attack, a man with no apparent direct links to the Islamic State or Al-Qaeda killed four people near British parliament.

Police were concerned the group may conduct a similar attack, possibly on one of many tourist attractions in Venice, which hosts around 20 million foreign tourists every year.

Italy has had relatively low levels of foreign fighters traveling to Iraq and Syria to join the Islamic State, only around 100 over the last few years, and much fewer than most western European nations. Within that small number, most are recent immigrants or second generation immigrants, and those who have only recently achieved residency status.

Some have pointed to Italy’s relative lack of established Muslim communities as a possible reason why. Considering that Italy only started seeing greater numbers of Muslim immigrants in the late 80’s and early 90’s, a primary demographic for foreign fighters—the second-generation immigrants—are only recently becoming adults.

Others have also noted Italy’s strict immigration and naturalization laws. It is relatively difficult to become an Italian citizen, and it is relatively easy to deport non-citizens and those suspected of homegrown jihadism or radicalization. Many suspects have been deported before there has been the opportunity to develop significant operating cells.

Italian police have said they will issue a statement regarding the arrests later in the day on Thursday.