Attackers shot dead a lawyer and his two sons aged 12 and 15 in Karachi on Tuesday in a suspected sectarian attack.

Attackers shot dead a lawyer and his two sons aged 12 and 15 in Karachi on Tuesday in a suspected sectarian attack, police said.

The men, on a motorbike, gunned down high court lawyer Kausar Saqlain and his sons Owais Abbas and Mohammad Abbas as he took them to school.

Karachi, a city of 18 million people, contributes 42 percent of Pakistan's GDP but is rife with murders and kidnappings and has been plagued for years by ethnic, sectarian and political violence.

Also Tuesday, gunmen shot dead a female anti-polio worker in northwest Pakistan, police said, the latest in a series of deadly attacks on vaccination teams.

The two attackers on a motorbike opened fire on the team as they went to administer polio drops on the edge of the city of Peshawar, near the restive Khyber tribal region where the military has been battling homegrown insurgents with links to the Taliban.

"One lady worker was killed and another wounded in the attack on the first day of a three-day campaign meant for areas on the outskirts of Peshawar," local police official Shafi Ullah told AFP.

Lawyers boycotted proceedings of the provincial High Court on Tuesday to mourn and condemn the death of Saqlain and his two sons.

"We strongly condemn the killings of our colleague and his two sons and we called off activities at the court," said Mustafa Lakhan, president of the Sindh High Court Bar Association.

However, A roadside bomb has hit a police patrol on Monday in Pakistan's troubled northwest killing five officers, police said.

The incident took place during a routine patrol in the remote mountainous Shangla district, 230 kilometers (143 miles) northeast of Peshawar, the main town of northwestern Khyber Pakhtunkhwa province.

"It was an IED which hit their vehicle. All the five policemen died on the spot," district police chief Mohammad Hussein told media outlets.