Why are the Hazaras being killed?

The Hazaras have been living in Pakistan for centuries. One of our army commanders (General Musa) was from the Hazara community. They have served the country ever since independence, and many of them have sacrificed their lives to save Pakistan. Yet they are being killed. Many have migrated, they have been threatened to leave Quetta, but the government has done nothing to ensure their security.
Why are the Hazaras being killed? It seems their crime is that they belong to the Shia sect. Another disadvantage for them is that they are easily recognizable, having Mongoloid features. So it is easy to single them out and shoot them. Unfortunately, those who are doing the killing are just like those who murdered Pakistanis living in East Pakistan, which became Bangladesh in 1971. Yet they refuse to admit it. They blissfully claim that all the killing was done by Hindus living in East Pakistan.
Of course, those who claim to be the guardians of Pakistan's ideology don't realize that by killing Hazaras, Pakistan is getting a bad name in the comity of nations. How long will they go on with this ostrich-like mentality? Don't they realize that diversity and pluralism are a country's strength, that the Arab countries have not produced any nuclear scientists or Nobel Prize winners because they drove away people of other religions from their lands?
The Hazaras should be protected, and the government will be responsible if it doesn't take steps to prevent fundamentalists from killing them.