Ajmer has been a peaceful city for a long time with both hindus and mulims and people of all other place living in peace.
Near Ajmer is Pushkar with the only Bramha temple in the world. Ajmer has been a place of religious diversity and where religious diversity is respected and cherished.
It is very clear that anti India people are doing this kind of stuff. Cause a hindu knows that Pushkar is just as vulnerable as dargah and vice versa for a muslim.
This has to be a handiwork of non-Indian viz. Pakistani.. or god knows what (could be politicians as well aka. Jinnah)... to create separation in people.
May god help the injured and give peace to the dead. And courage to those who have lost their loved ones.