ISLAMABAD - Four policemen were killed when some unknown gunmen attacked a police check post in Pakistan's southern port city of Karachi on Sunday night, local police said.

Fayyaz Laghari, inspector general of Sindh police said that some unidentified gunmen on motorbikes opened fire at four policemen standing at a check post of the main highway of Karachi, the capital city of the country's southern Sindh province.

The attack took place at about 9:20 pm local time and the assailants fled the scene following the attack.

No group claimed responsibility for the attack yet.

The attack on police took place shortly after the city was jolted by twin blasts, targeting a residential area in the neighboring Abbas Town area. The blasts left at least 28 people dead and over 60 others injured.