Updated 4:44 p.m. ET
A series of bombings in different parts of Pakistan killed 115 people on Thursday, including 81 who died in a sectarian attack on a bustling billiard hall in the southwest city of Quetta, officials said.
The blasts punctuated one of the deadliest days in recent years in Pakistan, where the government faces a bloody insurgency by Taliban militants in the northwest and Baluch militants in the southwest.
The country is also home to many enemies of the U.S. that Washington has frequently targeted with drone attacks. A U.S. missile strike Thursday killed five suspected militants in the seventh such attack in two weeks, Pakistani intelligence officials said.
"These attacks serve as a powerful reminder of unsettled conditions across Pakistan" a western diplomat in Islamabad told CBS News' Farhan Bokhari. The diplomat, who spoke on the condition of anonymity, said the attacks were also "indicative of an extremely tough environment in the next few months" due to this years' election campaign, which will precede parliamentary elections between March and May.
The billiard hall in Quetta, the capital of Baluchistan province, was hit by twin blasts about 5 minutes apart on Thursday night, killing 81 people and wounding more than 120 others, said senior police officer Zubair Mehmood.
The billiard hall was located in an area dominated by Shiite Muslims, and most of the dead and wounded were from the minority sect, said another police officer, Mohammed Murtaza. Many of the people who rushed to the scene after the first blast and were hit by the second bomb, which caused the roof of the building to collapse, he said.
Police officers, journalists and rescue workers who responded to the initial explosion were also among the dead, police said.
The sectarian militant group Lashkar-e-Jhangvi claimed responsibility for the attack to local journalists. One of the group's spokesmen, Bakar Saddiq, said the first blast was carried out by a suicide bomber and the second was a bomb planted in a car and detonated by remote control.
Radical Sunnis groups often target Pakistan's Shiite minority, whom they believe hold heretical views and are not true Muslims.
Earlier in the day, a bomb targeting paramilitary soldiers in a commercial area in Quetta killed 12 people and wounded more than 40 others, said Shakeel, the senior police officer.
The United Baluch Army, a separatist group, claimed responsibility for the attack on the soldiers in calls to local journalists.
Elsewhere in Pakistan, a bomb in a crowded Sunni mosque in the northwest city of Mingora killed 22 people and wounded more than 70, said senior police officer Akhtar Hayyat.
No group claimed responsibility for the attack.
The violence comes as the Obama administration prepares to draw down U.S. troops from Afghanistan. The White House has reason to be concerned if a breakdown across Pakistan makes the country unsafe, Bokhari reports.
"The U.S. will need Pakistan's help to take its troops and equipment out of Afghanistan," the western diplomat in Islamabad said. "Clearly, a Pakistan surrounded by growing distress will just add to the anxieties in Washington."