Pakistan has seen a series of attacks targeting election rallies just days before voters go to the polls on Thursday.
Authorities are stepping up security at polling stations.
Pakistan media say an explosion in the southwestern province of Baluchistan killed four people and injured six others. They were attending a rally in support of former prime minister Imran Khan's Pakistan Tehreek-e-Insaf party.
Elsewhere in the province, three children were injured when a hand grenade was thrown at an election office of the Pakistan People's Party led by former foreign minister Bilawal Bhutto Zardari.
The media say both incidents are believed to have been terrorist attacks.
In past elections, supporters of different candidates have clashed at polling stations, resulting in casualties.