Correspondents say at least three people were injured in Mianwali (Punjab) and Mardan (KPK) as rival groups clashed. However, the polling continued in Mianwali due to meddling of elders.
They incident of violence have been reported from NA-140 Kasur (Punjab), PP-44 Mianwali (Punjab) and NA-168 Vehari (Punjab), NA-9 Mardan (KPK) where exchange of fire happened between the rival political groups.
Voting in Vehari and Mardan could not be resumed after the clashes so far.
Law and order situation also remained tense in PS-57 Badin where armed men moved freely in polling booths.
Bogus voting continued in NA-155 Rahim Yar Khan where votes cast votes on expired, color copies and Photostat of National Identity Card (NIC).
By-polls are being held on six National Assembly seats, mostly fell vacant after PPP, ANP and PML-N lawmakers resigned to join the Imran Khan-led PTI, and four provincial assembly seats, two each in Punjab and SIindh.