At least 28 people were killed on Wednesday by two separate bomb blasts outside the offices of election candidates in southwestern Pakistan, on the eve of a national vote marred by violence and allegations of poll rigging.

More than half a million security officers were deploying ahead of Thursday’s election, with authorities distributing ballot papers to more than 90,000 polling stations.

There have been multiple security incidents in the run-up to the vote, with at least two candidates shot dead and dozens more targeted in attacks across the country.

Two bombs in Pakistan’s southwestern province of Balochistan have killed at least 28 people, officials said, with dozens more injured.

The twin blasts on Wednesday came a day before elections. The attacks targeted the election offices of political parties in the restive region.

The first blast, which killed 16 people, took place at the office of independent election candidate Asfandyar Khan Kakar in Pishin district near the border with Afghanistan, said Jan Achakzai, Balochistan’s caretaker information minister. More than 20 people were reported wounded.

Terrorists attacked two campaign offices in Pakistan’s restive western Balochistan province on Wednesday, a day before the country’s general election, killing 29 people and wounding 40 others.

Seventeen people died and 30 were wounded in the first attack, which took place shortly after noon local time when a suicide bomber struck the campaign office of Asfandyar Khan Kakar, a former minister and independent candidate for the provincial assembly constituency of Pishin, a district close to Pakistan’s border with Afghanistan.