The Muslims in Bangladesh who did this consider the Ahmadiyas heretics, and thus justifiably to be killed. Not a few would-be Muslim reformers in Bangladesh and elsewhere suspect this would be their fate also, and thus keep silent. From DPA via M&C, with thanks to Twostellas:
Dhaka – Suspected Islamic militants on Friday burned down a mosque and carried out bomb attacks on two other places of worship of the minority Ahmadiya sect in eastern Bangladesh, officials said.
Witnesses said the Ahmadiya mosque was razed to the ground after it was set ablaze by activists of a local anti-Ahmadiya group which wants the sect to be officially declared non-Moslem.
At least three people were injured in the fire which had quickly engulfed the mosque in the bordering town of Brahmanbaria, about 110 kilometres east of the capital Dhaka….
A rescue worker said there were a few people inside the mosque when the arson attack took place.
Residents said fire-bomb attacks were carried out on two other Ahmadiya mosques in the town but no casualties from these incidents were reported….
Extremist Sunni groups want the government to declare the Ahmadiyas non-Moslems because of religious differences on the status of Islam’s prophet Mohammed.
Most Ahmadiya religious publications are banned in Bangladesh, an Ahmadiya leader said.