The Pakistani Taliban claimed responsibility Sunday for a suicide bombing that killed four paramilitary guards in the southwestern city of Quetta.

The attack targeted Pakistani Frontier Constabulary (FC) guards in the Mian Ghundi neighbourhood of the city -- around 140 kilometers (87 miles) from the frontier with Afghanistan -- where Hazara Shiite merchants were selling vegetables.

The bomber "targeted the FC elements with an explosives-laden jacket and an explosives-laden motorcycle", on the Mastung road in Quetta, the Tehreek-e-Taliban Pakistan (TTP) said in a statement cited by the SITE Intelligence Group.

A spokesman for the police's Counter-Terrorism Department confirmed the attack.

Three died immediately in the blast, with another officer dying later of his wounds, said Azhar Akram, a deputy inspector general of police.

Akram told AFP that 17 guards and two civilians were wounded in the blast, adding that three are in critical condition.

The TTP claimed more than 30 FC personnel were killed and wounded in the attack.

Pakistani Prime Minister Imran Khan condemned "the TTP attack on FC Checkpost" in a tweet from his office, offering his condolences and concern for the recovery of the wounded.

"The PM pays tribute to the security forces and their sacrifices to keep nation safe by thwarting foreign-backed terrorist designs," his office added.

Quetta is home to approximately 500,000 Hazaras, who mostly live in an ethnic enclave on the edge of the city.

The community has long been targeted by the Islamic State and other militant Sunni groups, who see them as a heretical sect.

A series of bombings carried out by a Pakistani sectarian militant group in 2013 killed over 200 Hazaras in the city.

Frontier guards have also been targeted by Baloch insurgents, who have been waging a simmering insurgency for greater autonomy.