At least six people were killed and 35 injured Tuesday in a bomb attack during morning rush hour on the outskirts of Pakistan's northwestern city of Peshawar, officials said.

The bomb exploded during a traffic jam in the Wazir Dhand district just outside city limits, on a road linking the Khyber tribal region and Peshawar.

‘We have received six dead bodies and 35 injured from the blast site in Wazir Dhand area,’ including a seven-year-old child, said Toheed Zulfiqar, a public relations officer at Peshawar's Hayatabad Medical Complex.

Six of the injured are in serious condition, she said.

A local official said the attack apparently targeted a tribal police official.

‘We have received reports that it was a suicide attack but we are yet to confirm this information,’ said Ismatullah, a Khyber tribal district administration official. He also put the death toll at six.

Khyber is one of Pakistan's seven tribal districts situated next to Peshawar and bordering Afghanistan.

The mountainous forest regions have for years been home to some of the world's most notorious militants linked to Al-Qaeda or the Taliban.

Islamabad launched a military offensive in 2014 that has reportedly killed thousands of militants and pushed the rest over the border to Afghanistan, resulting in improved security inside Pakistan.

However, militants associated with Pakistan's homegrown Tehreek-e-Taliban Pakistan occasionally carry out attacks from bases in Afghanistan.