Gunmen have opened fire on a bus carrying Shia Muslim worshippers in Pakistan's city of Karachi, killing seven and wounding seven, police said.
Karachi police said it was a highly organised act of terrorism
The bus was carrying about 20 Shia Muslims to Friday afternoon prayers, said police official Athar Rashid Butt.
No one has yet said they carried out the attack in the west of the city.
However in recent years, sectarian violence between Sunni Muslims and minority Shias has killed hundreds.
Karachi police said the latest attack was a highly organised act of terrorism.
The bus had been carrying both Sunnis and Shias but the raid occurred after the Sunnis had been dropped off at their mosque.
Police said the gunmen tracked the bus on two motorcycles and fired dozens of rounds before escaping.
Three of the wounded were in a critical condition.
The worshippers were employees of a defence department research body
called the Space and Upper Atmospheric Research Organisation, police said.
No arrests have yet been made.
A Shia political party blamed the attack on two outlawed Sunni groups.
Medics rushed to the scene
Hasan Turabi, regional chief of the Tehrik-e-Islamia group,
told the AFP news agency that Lashkar-e-Jhangvi and Sipah-e-Sahaba Pakistan - which he called the "local operators of al-Qaeda" - were to blame.
"I fear more incidents of this nature will occur and I demand that operations should be conducted not only on the border with Afghanistan but also against local al-Qaeda operators," Mr Turabi said.
He was referring to the Pakistani army's operation against al-Qaeda on Thursday along the Afghan border in South Waziristan. Eight al-Qaeda suspects died and 18 were arrested.
Pakistan's Shia and Sunni Muslims have suffered many attacks by extremist groups within their communities in recent years.
The worst attack this year came in July when about 50 Shia worshippers were killed in a mosque in the north-western city of Quetta.
Lashkar-e-Jhangvi said three of its suicide attackers were responsible.
In June, two gunmen on a motorbike opened fire on a vehicle containing Shia police recruits in Quetta, killing 11.