Four people were killed and 20 others injured when a suicide bomber blew himself up alongside a paramilitary vehicle in Quetta, the capital city of Pakistan's southwest Balochistan Province, on Sunday morning, local reports said.

The incident happened at about 7:30 a.m. local time when a suicide bomber on a motorcycle packed with 6kg (13 pounds) of explosives rammed a vehicle in an FC convoy, Azhar Akram, deputy inspector general of the Quetta police, told Reuters.

The injured people including FC personnel and passersby were shifted to a nearby hospital where several of them were said to be in critical condition, according to Xinhua citing rescue officials. 

The Tehreek-e-Taliban Pakistan (TTP) claimed responsibility for the attack. 

TTP is a terrorist organization designated by the Pakistani government and the international community universally.

Pakistani Prime Minister Imran Khan later condemned the suicide attack.

"Condemn the TTP suicide attack on FC checkpost, Mastung road, Quetta. My condolences go to the families of the martyrs & prayers for the recovery of the injured. Salute our security forces & their sacrifices to keep us safe by thwarting foreign-backed terrorists' designs," he tweeted.

(With input from Xinhua, Reuters)