Islamabad, October 3 (IslamOnline.net) - At least six Shiite Muslims were killed and eight others injured in what police said was a “sectarian terrorist” attack on a bus carrying a group of people moving to a Shiite mosque for Friday prayers in the southern port city of Karachi.

Two unidentified gunmen riding a motorbike opened fire on the bus when it was approaching a mosque in the outskirt of Karachi, Karachi city Police chief Tariq Jamil told Islamonline.net on the phone.

"Five people were killed on the spot while seven were injured. Three of them are in a serious condition,"

One of the injured later died at the hospital, an official at Karachi's Civil Hospital told Agence France-Presse (AFP).

Jamil said it was a sectarian killing.

The victims were employees of a defense research body called Space and Upper Atmospheric Research Organization (SUPARCO). They routinely traveled to a local mosque on Friday, Islam's holy day, to offer prayers, Jamil said.

The dead included a soldier from the Pakistan army's medical corps, residents said. Witnesses said the attackers intercepted the vehicle in what appeared to be targeted killing.

"The attackers came on a motorbike and blocked the way of the van. They first fired at the driver, who died on the spot. Then the attackers sprayed bullets into the van from all sides," said a survivor.

"I and others tucked under the seats to save ourselves from the bullets," he said, requesting not to be identified.

The police did have proper security arrangements at the mosque, like they have around every mosque in Karachi. But no security was present for the bus carrying 20 people to mosque.

Jamil said the police was not informed about the group of people moving together on their way to the mosque, otherwise proper security cover could have been provided in the face of growing sectarian violence in which hundreds of people have been killed over the last few years.

News of the shooting came shortly after reports of another attack, in the north of the country, when assailants fired a rocket at a train killing the conductor and wounding four others, CNN reported.

That attack Friday morning occurred in the town of Much, about 150 km (92 miles) east of the city of Quetta.

Jamil said it was too early to blame any particular group for the Karachi attack but some of the outlawed Sunni groups have been involved in similar attacks against Shiite community in Pakistan which has a history of a bloody religious violence.

But a Shiite political party claimed the blame on two outlawed extremist outfits.

"Lashkar-e-Jhangavi (LJ) and Sipah-e-Sahaba Pakistan (SSP) are the local operators of al-Qaeda and this (attack) is part of the appeal made by Al-Zawahiri to topple Pervez Musharraf's government," Hasan Turabi, regional chief of the Shiite Tehrik-e-Islamia group, told AFP.

President Pervez Musharraf, whose country is a key ally in the U.S.-led war on terror, last year banned LJ and SSP in an effort to curb sectarian violence, which has claimed the lives of some 4,000 people in the past few years.

Shiites comprise about 20 percent of Pakistan's Sunni-dominated 140 million population.

Pakistani police investigators suspect LJ activists were also involved in attacks on Christian and Western targets last year, including the murder of U.S. journalist Daniel Pearl, according to AFP.

Minority Shiite and majority Sunni gunmen have often been blamed for the tit-for-tat killings taking place in the country for the last two decades now.

Despite this long history of religious violence the two communities normally live in peace.

The Karachi shooting is the latest in a series of attacks to shake the southern port city.