BERLIN (Reuters) - German police said on Friday five people were injured when a fire broke out at a refugee shelter in the town of Heppenheim in the West German state of Hesse. There was no immediate indication of how the blaze began. Germany, which expects the influx of refugees and migrants to quadruple to about 800,000 this year, has witnessed more than 100 arson attacks on asylum shelters in recent months.

"One resident who tried to rescue himself by jumping out of a window from the second floor was seriously wounded," police spokeswoman Christiane Kobus said in a statement.

Four people were slightly injured by smoke poisoning, she said. More than 60 refugees from countries such as Syria, Iraq, Somalia and Ethiopia were accommodated in the three-storey residential building.

"The fire was extinguished quickly. According to initial findings, the fire emerged behind the entrance door for unknown reasons," Kobus said. Police and state prosecutors had started an investigation into the cause of the fire, she said.

Most of the recent attacks on asylum shelters in Germany have been on empty buildings slated to become shelters. However, politicians have warned that it was only a matter of time before refugees might be hurt.

Europe is facing its worst refugee crisis since the Yugoslav wars of the 1990s. The crisis has strained the European Union's asylum system to breaking point, divided its 28 nations and fed the rise of right-wing populists.