Police in Italy have arrested two American students.
They the pupils are connected to the killing of a policeman in central Rome.
According to a statement from Italian military police Carabinieri, the students are also being held for attempted extortion.
The students allegedly stabbed 35-year-old Mario Cerciello Rega to death on Friday.
Another police officer was injured in the incident.

US military: ready to strike Iran's power plants, energy industry if ordered
Hopes for deal to end Iran war grow, but nuclear issues unresolved
Pope Leo, in Cameroon, decries world 'ravaged by tyrants'
White House denies US requested ceasefire, says new talks may happen in Pakistan
Netanyahu: Israel military continues to strike Hezbollah
