Trust me guys, this is snow and frozen rain mixture, in those pictures, at some parts its just snow, like where you see it accumulated on the roads. The hail does not accumulate and become sleet, mainly snow and frozen rain form this slush of sleet.
Where as Hail mainly results from Monsoon Rains. Monsoons winds originate from East. Warmer areas of Bay of Bengal and the rain clouds form higher up in the atmosphere, way above the stratosphere....and in Pakistan, I remember it use to Hail during Summers and never in Winter.
This snow and frozen rain is originating from Northern Winds of Winter.
Its mainly due to global warming and cooler air drifting down from the North to Southern areas. But since Islamabad is in close proximity to Murree, the environment and location for snow was ideal, just needed a tad bit of help from Cooler Winds comming down from the North.
God Bless, enjoy while it lasts. Hopefully, the Ice Caps on North Pole don't melt out soon, so we can have some more nice winters like this in Pakistan... They will eventually, due to global warming, its a fact. The whole Earth will experience rise of between 2 to 5 Degrees Celcius in the next few decades, which can disturb patterns of Global Winds tremendously.