ISLAMABAD - At least three people were killed and 23 others injured when a bomb went off near a mosque in Pakistan's southern port city of Karachi on Sunday night, said an official.

Sharfuddin Memon, Advisor to Home Minister of Sindh Province where Karachi is its capital, said that the blast which hit Mustafa Mosque, the largest mosque for Shiite Muslims in the city, on Sunday night, killed at least three Shiite Muslims including a woman and wounded 23 others.

The injured also include five members of Rangers, a paramilitary force in Pakistan, who were posted at the mosque to protect the prayers, confirmed a spokesman of Rangers. ?

Hospital sources said that at least six wounded people were in critical condition and the death toll may further rise. ?

The blast also caused a blackout in the nearby areas and destroyed at least seven vehicles and motorbikes on the site, said local media.

The blast occurred at about 9:10 pm local time when a bomb fixed on a motorbike parked near the mosque went off as people were leaving the mosque through its main gate after Muharram prayers.

It was a home-made bomb denoted through a remote control device, said Chaudhry Aslam, Superintendant Police of Criminal Investigation Department of Karachi.

Bomb disposal squad officials believed that an estimated three to four kg of explosives were used in the bomb.

No group has claimed the responsibility for the attack yet.

The attack could be a reaction to the recent arrest of several terrorist suspects involved in the sectarian attacks, said Chaudhry Aslam.

The attack has sparked off a strong protest from the local Shiite Muslims and a Shiite Muslim group, Tahafuz-e-Azadari Council Pakistan, has announced a three-day mourning for the victims of the blast.

Both the Pakistani President Asif Ali Zardari, who himself is a Shiite Muslim, and officials at the federal and provincial levels as well as major party leaders have strongly condemned the attack.

Sunday night's bomb attack is the most serious sectarian attack reported in the country during Muharram, the first month of the Islamic calendar which started on Friday. Though fighting is strictly prohibited during Muharram, extremists from both Sunni and Shiite sides tend to choose this time to attack each other.