A policeman who had just returned from his honeymoon was stabbed to death in Rome while trying to make an arrest, reports AFP.
Mario Cerciello Rega was attacked around 3 am CEST on Friday.
Two teenage Americans, who were staying in a luxury hotel and had plane tickets to leave on Friday night, were later arrested.
Rega was trying to detain suspects of a bag theft when the stabbing happened.
The victim of the bag theft was a dealer, according to AFP, who had sold them "cocaine", which was actually aspirin.
To get their revenge, the suspects stole the bag and arranged to meet the dealer to exchange it for €100, added AFP, citing Italian media.
The dealer alerted police to the meeting and that's when the plain-clothed Rega tried to make the arrest.
Police murders are rare in Italy and politicians of all parties have expressed their horror of the situation.
Interior Minister Matteo Salvini tweeted the perpetrator should do "hard labour in prison for the rest of their days."
In another tweet, he offered his condolences and said the victim had married less than two months before the incident.
The case has shaken Italy with mourners coming to leave flowers outside of the police station where Rega worked. Italian state police stopped their cars outside of the Carabinieri headquarters and sounded their sirens to pay tribute.