As per initial reports, unidentified people set fire to polling material at one of the stations situated in Kesrar Sama area in Tharparkar as polling concluded and the vote count was underway in by-polls of the district's NA-221 constituency on Sunday.
Police and Rangers personnel rushed to the area and arrested PTI's Amanullah Samon and four other workers.
Following two days of intense politicking, against the Pakistan Muslim Leauge-Nawaz (PML-N), in the aftermath of the by-polls in Punjab and Nowshera, the ruling Pakistan Tehreek-e-Insaf (PTI) is now vying with the Pakistan Peoples Party.
The main candidates for the constituency are PPP's Pir Ameer Ali Shah and the ruling party's Nizam-ud-Din Rahmon.
Also read: Internal rifts cost PTI dearly in by-polls
The polling continued uninterrupted until 5pm, with a total of 12 candidates vying for the coveted slot. There are a total of 281,900 registered voters in the constituency.
As many as 318 polling stations have been established in the area, of which 130 have been declared sensitive, while 95 have been declared highly sensitive.
In order to make the process independent and transparent, around 4,000 police personnel and 1,000 personnel from the paramilitary force have been deputed at the polling stations. The NA-221 seat fell vacant after the demise of PPP's Pir Nur Muhammad Shah Jilani a few months ago. He had won the seat in the 2018 general elections in the country.