After a row with his girlfriend, the 27-year-old shooter grabbed a gun from his car and fired randomly...
Populist figures are tapping into anger about immigration and growing inequality.
Officials are probing "indications of a possible link" to the Nov. 13 Paris attacks
The political rift is greater across Europe, with Hungary accusing Berlin of encouraging the influx.
Austria said 9,000 people had crossed from Hungary on Saturday.