QUETTA, Pakistan – A series of bombings killed 115 people across Pakistan on Thursday, including 81 who died in twin blasts on a bustling billiards hall in a Shiite area of the southwestern city of Quetta.

Pakistan’s minority Shiite Muslims have increasingly been targeted by radical Sunnis who consider them heretics, and a militant Sunni group claimed responsibility for Thursday’s deadliest attack — sending a suicide bomber into the packed pool hall and then detonating a car bomb five minutes later.

It was one of the deadliest days in recent years for a country that is no stranger to violence from radical Islamists, militant separatists and criminal gangs.

Violence has been intense in southwest Baluchistan province, where Quetta is the capital and the country’s largest concentration of Shiites live. Many are ethnic Hazara who migrated from Afghanistan.

The billiards hall was located in an area dominated by the minority sect. In addition to the 81 dead, more than 120 people were wounded in the double bombing, police said. The dead included police, journalists and rescue workers who responded to the initial explosion.

Lashkar-e-Jhangvi, a Sunni militant group with strong ties to the Pakistani Taliban, claimed responsibility for the attack. Hazara Shiites have been the targets of dozens of attacks by Lashkar-e-Jhangvi in Quetta over the past year.

Human Rights Watch sharply criticized the Pakistani government for not doing enough to crack down on the killings and protect the country’s vulnerable Shiite community. It said more than 400 Shiites were killed in targeted attacks in Pakistan in 2012.