PUNO Peru - on Wednesday announced a curfew in the southern Puno region in a bid to suppress violent protests, a day after 18 people were killed in clashes between demonstrators and security forces. Prime Minister Alberto Otarola said the three-day nighttime curfew would run from 8:00 pm to 4:00 am (0100 to 0900 GMT). In total 40 people have been killed over a month of protests demanding the departure of President Dina Boluarte, who took over after the ouster and arrest of then president Pedro Castillo on December 7. On Tuesday Peru’s prosecutor’s office said it was opening a genocide investigation against Boluarte and other top officials as a result of the deaths. The Puno region that borders Bolivia and is home to many Aymara Indigenous people has become the epicenter of the protest movement led by Castillo supporters. Overnight, protesters looted shops and attacked police vehicles in the region. Most of the bloodshed there took place when protesters tried to storm the airport in the city of Juliaca that was being guarded by security forces. Fourteen people were killed, many having suffered gunshot wounds, according to an official at a Juliaca hospital. Three more people died during the ransacking of a shopping center in Juliaca while the last known victim was a police officer who the United Nations said died after his vehicle was set on fire The government has defended the actions of the security forces in Juliaca.