Pakistani authorities began rounding up undocumented foreigners, most of them Afghans, on Wednesday, ahead of a midnight deadline for them to leave or face expulsion.

The removal of people to temporary holding centers began a day earlier than previously announced. The interior ministry said 140,322 people had already voluntarily left after days in which trucks piled high with belongings and crammed with people have jammed major roads out of the country.

Pakistan set the Nov. 1 start date last month for the expulsion of all undocumented immigrants, including hundreds of thousands of Afghans. It cited security reasons, brushing off calls to reconsider from the United Nations, rights groups and Western embassies.