The officer was killed on Thursday morning in the Tank area of Pakistan's northwestern Khyber Pakhtunkhwa region, according to local police officials, Sky News reports.
The incident reportedly took place at a polling station in the town of Kot Azam, according to the news agency Reuters, quoting local media.
It comes as people have begun casting their ballots in the country's highly-charged election - the build-up to which has been marred by violence and claims of fraud.
On the eve of Thursday's election, bombs struck two political offices in southwestern Pakistan, killing at least 30 people.
Tens of thousands of police and paramilitary forces have been deployed at polling stations to ensure security.
Mobile phone service has also been suspended across the country in what the government has described as a "security measure".
MNA/PR