ISLAMABAD, July 22 (Xinhua) -- At least two people including a candidate for Pakistan's upcoming general elections were killed and three others injured in a suicide attack at a political rally in the northwest region of the country on Sunday, police said.

District police officer Manzoor Afridi said that Ikramullah Khan Gandapur of the Pakistan Tehreek-e-Insaf (PTI) and his driver, who were seriously injured in the attack, succumbed to their injuries during treatment at a hospital.

Afridi said a suicide bomber exploded his explosives-laden vest near the vehicle of Gandapur when he was passing through his native village in Kolachi area of Dera Ismail Khan, a district in the country's northwest Khyber Pakhtunkhwa province.

Gandapur came under the attack when he was leading a political rally as part of his campaign to contest for a provincial assembly seat in the country's upcoming general elections on July 25.

This is the third candidate contesting for Pakistan's July 25 election who lost his life in a suicide attack.

Police said that eight to ten kilograms of explosives along with ball bearings were used in the attack.

The police officer said that 13 police personnel were assigned to Gandapur, but he chose to travel without informing his police guards, adding that the security forces had warned of death threats to Gandapur on Saturday.

No group has claimed responsibility for the attack yet.

Gandapur served as minister for agriculture and livestock from 2013 to 2018 in the Khyber Pakhtunkhwa province.

Following the candidate's assassination, the Elections Commission of Pakistan has postponed the elections for his constituency.

At least 170 people have been killed and over 200 others injured in terrorist attacks at the public rallies in different areas of the country in July so far.