An Italian court convicted 13 police officers Thursday of violence against protesters during the 2001 Group of Eight summit in the northern Italian city of Genoa.

The officials were charged with inflicting violence, abusing their powers and other offenses during a pre-dawn raid on a school where the protesters were staying.

At the end of a three-year trial, the court in Genoa handed down jail sentences ranging from one month to four years and ordered those convicted to pay damages to the victims.

Judges cleared 16 other officers on trial, sparking anger and shouts of “shame, shame” from activists gathered at the courtroom late Thursday. The rulings can be appealed.

Police raided the Diaz school at the end of a G-8 summit marred by massive protests, with some groups turning violent and rampaging through the city. The officers said they were acting on a tip that violent demonstrators were hiding there.

Many of the Italian and foreign activists in the school said they were attacked while they slept and gave accounts of police brutality. The serious injuries reported and the images of blood plastering the walls and floors of the school sparked an outcry in Italy and abroad.

At least one of the officers convicted Thursday, Michelangelo Fournier, confirmed some of the allegations, testifying that police beat up defenseless people and left the school looking like a “butcher’s shop.” Fournier, a top official in Rome, received a two-year sentence.

The violent riots by anti-globalization activists during the July 2001 summit left one protester dead, more than 200 people injured, 240 detained and millions in damages.

This summer a court convicted 15 Italian officials of abusing protesters in detention at a police garrison in Genoa.

Last year, judges also convicted 24 protesters of devastation and looting, giving them sentences ranging from five months to 11 years in prison.