Four Afghan civilians have been killed in two separate incidents, the authorities said Monday.

At early Monday morning, one civilian was killed when a sticky bomb attached to his vehicle was detonated in western Kabul.

"The vehicle, with one person aboard, was running along a main road in Mirwais Mina district of western Kabul at around 6:30 a.m. local time. The sticky bomb was detonated, killing the man on the spot," an Interior Ministry source told Xinhua, adding that the identity of the victim remained unknown.

In addition, three members of a family were killed when unidentified gunmen opened fire on their motorcycle in Trikh Nawar area, Marja district of the southern province of Helmand overnight, the provincial government spokesman Omar Zwak told Xinhua, adding that the police are investigating the motive behind the attack.

The UN Assistance Mission for Afghanistan has said that more than 1,300 civilians were killed and over 2,500 others injured in Taliban-led attacks and violent incidents in Afghanistan from January to June this year.