Islamabad, Pakistan - A suicide bomber has killed at least seven police officers and wounded 22 others in the southwestern Pakistani city of Quetta.

The attack targeted a truck carrying police personnel on the city's main Saryab road on Wednesday morning, local police official Muhammad Akbar told Al Jazeera.

Provincial home minister Sarfaraz Bugti, speaking to media at the site of the attack, said those attacked were "elite" officers.

Six police officers and a civilian were killed and 22 wounded, said provincial chief minister Sanaullah Zehri, speaking to reporters at the hospital where the wounded were being treated.

"It was a suicide attacker who appeared to be in a car with between 70 to 80kg of explosives," Zehri said.

Television footage from the scene showed the mangled and scorched wreckage of the truck lying by the side of the road. Police cordoned off the area around the blast site immediately following the attack.

Quetta, the capital of Balochistan province, has often been at the centre of attacks by both religious armed groups such as the Tehreek-e-Taliban (also known as the Pakistan Taliban) and armed ethnic Baloch separatists fighting for independence from Pakistan.

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"The people of Balochistan are fighting this war on the front line," Bugti said.

No group immediately claimed responsibility for Wednesday's attack. Balochistan has, however, increasingly come under attack from groups such as the Pakistan Taliban, the Islamic State of Iraq and the Levant (ISIL) and others.

Last week, five people were killed in an attack on the city's minority Hazara Shia Muslim community.

Earlier this month, a suicide bomber killed 18 people when he attacked a Sufi shrine near the town of Jhal Magsi, about 165km south of Quetta.

The province has also been the site of a decade-long armed separatist campaign by ethnic Baloch fighters who are fighting for independence in the resource-rich province.

Earlier this week, the Baloch Liberation Army, one of the main armed groups, claimed it killed two Pakistani security personnel deployed to protect the China-Pakistan Economic Corridor (CPEC) in the Panjgur district.

CPEC, a $56bn infrastructure project, will see a major trade corridor constructed from China's southwestern Xinjiang province that runs through the length of Pakistan, culminating in a major port in the Balochistan town of Gwadar.

The project envisages the linking of Chinese markets directly to Arabian Sea trade routes through the construction of roads, rail and other infrastructure, as well as the construction of at least 19 power generation projects across Pakistan.

Asad Hashim is Al Jazeera's digital correspondent in Pakistan. He tweets @AsadHashim