At least 12 people were killed in separate incidents of violence in Pakistan's southern port city of Karachi overnight, local media reported Thursday. ARY News reported that three students were killed and two others injured when some unknown gunmen opened fire at a restaurant in Gulistan-e-Jauhar area. The attackers on two motorbikes fled the scene following the attack, and the injured students were shifted to a nearby hospital. Enraged people took to the street to protest against the killing of students, pelting stones at police and setting ablaze push carts. Police dispersed the angry mob using tear gas. In a separate incident in the same area, some unknown gunmen opened fire at a car, killing one man inside. Police said that the deceased was a doctor who was shot dead as soon as he returned home from his clinic, becoming the latest victim of growing sectarian violence in the city. In another incident in Soldier Bazar area, three people were killed when some unknown militants opened fire at a shop. Earlier, police recovered two bullet-ridden bodies from North Nazimabad area of the city. The victims have not been identified yet. Three other people including a political activist were killed in separate incidents of firing. No group has claimed responsibility for the violent incidents. Karachi police said that they had arrested 92 alleged terrorists during 98 search operations carried out across the city on Tuesday and Wednesday. The police also seized huge quantity of arms and ammunition in the operations.