German police have arrested four men after finding possible bomb-making materials in their car at the border with Austria.
Federal police also suspect the car's 38-year-old Polish driver of trying to smuggle the other three men, aged 20, 29 and 37, into Germany, according to reports.
Police said the passengers are from Ivory Coast and Guinea.
Authorities said they found three pipes in the car, along with what appeared to be gunpowder and possible ignition devices, during a search on Thursday night at a border crossing near the town of Kiefersfelden.
Police say the materials could possibly be used to fashion crude pipe bombs, and that experts are trying to confirm whether the substance found is indeed gunpowder.