Excerpt from research done by Ravinder Kaur:
In the Partition migration history, June 3, 1947, is as important a day as the Partition itself. On this day then British governor- general Mountbatten announced the Partition Plan according to which the British would hand over power as early as August 1947 instead of June 1948 as planned earlier. The advanced date meant that the entire procedure of transfer of power had to be hurried up. This included handing over authority, division of assets and the territorial division of Punjab and Bengal provinces. Communal riots had already erupted in Rawalpindi district earlier in the month of March where 2,090 people died and 1,142 were seriously injured [Hansen 2002:117]. The fall of Khizar Tiwana government in Punjab following the Muslim League agitation led to widespread riots in Rawalpindi that soon engulfed Lahore, Amritsar, Jhelum, Attock and Multan. A particular feature of the March violence, besides the unprecedented number of deaths, was the number of people who sought refuge in the camps. An official estimate from the districts of Attock, Jhelum and Rawalpindi alone put the number of refugees at 60,000 who were in the camps either because they feared for their safety or their houses had deliberately been burnt (ibid:113). The growing uncertainty about the future course of events such as the drawing of boundary lines and the possible extent of communal violence, further proved cataclysmic in making people move away to perceived safer areas where their community was in the majority.
The upper middle class migration occurred quite early as a precursor to the impending mass migration in the months to follow. As a precautionary measure, many people with substan- tial properties and businesses left the trouble-prone areas long before the Partition took place. They would either take up temporary residences in Hindu-dominated cities or proceed to the hill stations of Simla or Mussorie for early summer vacation while waiting to see if the situation would normalise. They even took to sell their properties or exchange them with those Muslims on the other side of the border who were contemplating migration to Pakistan.
Link: http://jan.ucc.nau.edu/~sj6/ravinderkaurlastjourney.pdf