ROME -- Italian police on Thursday arrested three Kosovans in the city of Venice after one was caught on a phone intercept proposing they bomb the Rialto bridge while others lauded the recent attack in London. A minor was also detained.

Venice prosecutor Adelchi d'Ippolito said a search of a Venice apartment showed the suspects were getting in physical shape and watching videos of Islamic extremists on how to carry out knife attacks.

A phone intercept caught one saying: "You'll go straight to paradise because of all the infidels in Venice. Put a bomb on the Rialto." It wasn't clear if the reference was bluster or indicated an imminent threat.

The 16th-century Rialto arched bridge is one of Venice's iconic tourist draws, spanning the Grand Canal and featuring small shops on either side of its steps.

Authorities said the suspects -- identified as Fisnik Bekaj, Dake Haziraj e Arjan Babaj -- spoke among themselves about being ready to die for the jihadist cause and becoming particularly inspired after the recent attack in London. On March 22, Khalid Masood mowed down pedestrians on Westminster Bridge, killing three, and then fatally stabbed a policeman on the grounds of Parliament.

D'Ippolito said the suspects were "truly dangerous" and were suspected of plotting attacks both in Italy and overseas. But he added that they wouldn't have been able to carry out any attack in Italy since they were under such tight surveillance.

Italian police have made several arrests in recent years of suspected Islamic extremists, on allegations they were recruiting fighters for jihad in Syria and Iraq, were radicalizing others or were plotting attacks domestically.

Venice Mayor Luigi Brugnaro said all those detained in the early morning sweep Thursday had regular residency permits to live in Italy. He said in addition to the detentions, police searched 12 sites in Venice's centre, Mestre and nearby Treviso.