Amjad Sabri, a famous Pakistani Sufi singer, has been shot dead by unidentified gunmen in Karachi. He sang a type of devotional music called qawwali. (Reuters)

By firing at least three shots into a beloved musician's car in Pakistan's largest city, two gunmen ushered in one of the darker days in that country's quest for tolerance, art and peace.

The man shot dead was Amjad Sabri, 45, part of a duo with his brother, and a son of one of Pakistan's most renowned singers. The city was Karachi, which is racked by organized crime, kidnappings and assassinations. The gunmen's identities and whereabouts remain unknown.

The Sabri family sang a kind of music particular to South Asia's Sufi community. It is called qawwali. The Sabris were arguably the second-most famous qawwali singers after the late Nusrat Fateh Ali Khan, who introduced the form to the world beyond the subcontinent. There are millions of Sufis in Pakistan, India and Bangladesh.

Above all, qawwali is devotional music, and its songs are odes to love of God. They often conjure a relationship between the singer and God that is intensely personal, almost as if they are lovers. The Sufi tradition from which the music derives is unique to South Asia. Its practice often takes the form of mystical, musical folklore, and followers pay respects to dead Sufi saints at shrines big and small. Sufism preaches tolerance and peace, and is about as far as can be from the strict forms of Islam that have gained a foothold in Pakistan in the past generation.

And perhaps that is why Sabri was killed. Sufi shrines have been mercilessly attacked in Pakistan in recent years, as well as in Bangladesh, where similar hard-line groups have succeeded in recruiting large numbers of young people. Radical Islamists have also carried out bombings and executions targeting Pakistan's minuscule minority groups, including Christians and Ahmadi Muslims, as well as human-rights activists.

The Pakistani government has been accused of doing little to protect minorities. A draconian blasphemy law is often used to harass minorities, and Pakistan is officially an Islamic Republic. Unconfirmed reports have claimed that Sabri asked a provincial government for protection after he received death threats but didn't receive it. Some conservative politicians have called for the banning of qawwali music.

The song in the video above (apologies for the poor quality — the audio cuts out occasionally but comes right back) is called "Bhar Do Jholi," or "Fill my bag," and is one of the Sabri brothers' trademarks. Below is a translation of lyrics of a verse posted online by Hamza Shad, a student at the University of Chicago. They give a sense of the kind of earnest, folksy devotion that characterizes qawwali music.

شہِ مدینہ سنو اِلتجا خدا کے لئے
Shah-e-Madeena suno iltija Khuda ke liye
O King of Madinah, hear my plea, for God’s sake
کرم ہو مجھ پہ حبیبِ خدا، خدا کے لئے
karam ho mujh pe Habeeb-e-Khuda Khuda ke liye
Bestow your favor upon me, O Beloved of God, for God’s sake
حضور غنچۂ اُمّید اَب تو کھِل جائے
Huzoor ghuncha-e-ummeed ab to khil jaye
O Prophet, let the bud of my hopes blossom now
تمہارے در کا گدا ہوں تو بھیک مِل جائے
tumhaare dar par khada hoon to bheek mil jaye
I am a pauper at your door, here to seek alms
بھر دو جھولی میری یا محمد
bhar do jholi meri ya Muhammad
Fill my bag, O Muhammad
لوٹ کر میں نہ جاؤں گا خالی
laut kar main na jaaoon ga khaali
I will not go back empty-handed

Read more:

The world’s most bizarre YouTube star is from Pakistan. Here’s the proof.

Pakistan’s plan for tackling deforestation: A billion trees

A Pakistani girl ran away and converted to Islam. Now she cannot go back to her family.