More than a hundred people were killed in a series of bombings and shootings in Pakistan on Thursday.

In Pakistan's commercial capital, Karachi, 10 people were killed in two separate incidents.

According to local media, five people were shot dead on the outskirts of the city by assailants who fled the scene.

Five others were also shot dead by gunmen riding on motorcycles.

Gul Amin Shah, the father of one of the victims, said: "Six people, riding on three motorcycles, stopped the boys and then opened fire at them from close range."

Meanwhile, a bomb in a crowded Sunni mosque in the northwest city of Mingora killed 22 people and wounded more than 70, police said.

No group claimed responsibility for the attack.

District police officer Gul Afzal Khan was unable to provide many details about the cause of the blast.

"Various security agencies are working on it, and later we will be able to say whether this is an act of terrorism or not," he said. "But at this stage it looks like a cylinder blast."

There were also two deadly blasts in the southwest city of Quetta.

A bomb targeting paramilitary soldiers in a commercial area of the city killed 12 people and wounded more than 40 others, a senior police officer said.

And 81 people died in a sectarian attack on a bustling billiard hall.

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 billiard hall was hit by twin blasts about five minutes apart on Thursday night, killing 81 people and wounding more than 120 others, said a senior police officer.

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.

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.

Ameenullah Mengal, a local TV cameraman and eyewitness, corroborated that account.

"After the first blast everyone rushed to the scene, including journalists, police and rescue workers," he told the Associated Press.

"As we got to the scene, and rescue workers were moving wounded people, suddenly there was another blast and we were unable to see anything because of the darkness. Everyone was scattered here and there and the wounded were crying and lying on floor here and there."

The sectarian militant group Lashkar-e-Jhangvi claimed responsibility for the attack to local journalists.

One of the group's spokesmen 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.