Never ending bloodshed.

(WSJ) — The killing of 81 people in a Shiite area of Quetta on Thursday is the latest sign that a war by Sunni militants on minority sects in Pakistan is spiraling out of control.

The twin blasts on a Quetta billiard hall are part of a systematic attempt by Sunni extremists to wipe out the Hazaras, a Shiite ethnic group that emigrated to Pakistan from Afghanistan three generations ago.

Sunni gunmen with links to the Taliban for over a year have been targeting members of the Persian-speaking Hazara community, often in broad daylight, on the streets of Quetta, a lawless city in Pakistan’s southwest near the frontier with Afghanistan.

But the violence against Shiites hasn’t been restricted to Quetta and the restive southwestern province of Baluchistan, of which it is the capital. Shiites have increasingly been gunned down in Karachi, the southern financial capital. In August, militants wearing Pakistan army uniforms boarded a bus travelling into Pakistan’s Himalayas and shot dead over 20 Shiite passengers after checking their identity cards.

Human Rights Watch estimates around 400 Shiites were killed in Pakistan last year, an escalation of violence that highlights the failure of Pakistan’s security forces to bring extremist groups under control despite international pressure on Pakistan to rein them in.