An Afghan security force member inspects the site of an attack in Nangarhar province, Afghanistan, Aug. 25, 2018. At least three people were killed and four others wounded after an explosion occurred outside the provincial election office in Jalalabad city, capital of eastern Afghan province of Nangarhar on Saturday, a local official said. (Xinhua/Saifurahman Safi)

JALALABAD, Afghanistan, Aug. 25 (Xinhua) -- At least three people were killed and four others wounded after an explosion occurred outside the provincial election office in Jalalabad city, capital of eastern Afghan province of Nangarhar on Saturday, a local official said.

The initial information found that three people, including a suspected suicide bomber, died on the spot and four others injured after the blast occurred in front of the office in Police District 5 of the city at around midday, said a police officer who requested anonymity.

The victims were shifted to a hospital where one of the injured remained in critical condition.

Attaullah Khogyani, provincial governor spokesman, confirmed that the attack was a suicide bomb blast.

"We heard a huge blast at around 11:30 a.m. local time. The whole place has now been sealed off," an eyewitness told Xinhua.

The blast came as a protest was underway by the supporters of election candidates, he added.

No group has claimed responsibility for the incident but Taliban militants and militants of Islamic State are active in the province.

The capital city, 120 km east of Kabul, has been hit by series of terrorist attacks this year.