Several people were killed during unrest in Iran, Iranian media and rights groups said on Thursday, as the biggest protests to hit the Islamic Republic for three years over worsening economic conditions sparked violence in several provinces, Reuters reported. 

The semi-official Fars news agency reported that three protesters were killed and 17 were injured during an attack on a police station in Iran's western province of Lorestan.

"The rioters entered the police headquarters around 1800 (local time) on Thursday ... they clashed with police forces and set fire to several police cars," Fars reported, according to Reuters.