"I am standing right at the border to Hungary and am looking down. The streams (of people) keep coming," Hans Peter Doskozil, chief of police in Burgenland state, was quoted as saying by the AFP news agency.
He also said that they are "waiting for 17 or 18 double-decker buses to be able to take people to Vienna, maybe also towards Germany."
On Friday, Austrian Chancellor Werner Faymann said on his Facebook page that "because of today's emergency situation on the Hungarian border, Austria and Germany agree in this case to a continuation of the refugees' journey into their countries."
Around 10,000 migrants are expected to enter Austria from Hungary on Saturday, Austria’s Interior Ministry said as cited by local media.
The majority of migrants are expected to apply for asylum in Germany, Sweden and elsewhere in Western Europe. Munich, in southeastern Germany, is preparing for 8,000 migrants that are expected to travel by train through Austria.
A total of 340,000 people have reportedly entered the EU without proper documents thus far this year, compared to 280,000 in the whole of 2014.