Firefighters are battling a blaze that broke out in Berlin's Grunewald forest followed by numerous explosions at a police munitions storage facility.
Some 15,000 square metres of forest is burning, the fire department of the German capital said on Twitter on Thursday night, adding that "explosions are occurring", reports Xinhua news agency.
A restricted area of around 1,000 metres was set up around the perimeter of the fire.
A police helicopter and a drone are supporting the coordination of the operation.
The fire department said a firefighting helicopter and armoured vehicles from the German armed forces were also called in.
Fire department spokesperson Thomas Kirstein said more information was needed on the state of the site, adding that: "The operation will take a long time."
Meanwhile, Berlin fire department spokesperson James Klein told Deutsche Welle that Grunewald is used for the storage of ordnance, as well as fireworks and other objects that can explode.
The Grunewald munitions facility has been in operation since 1950. Alternative areas were either not available in Berlin or could not be approved, police said.
"Areas in Brandenburg were also examined, but these could not offer comparable storage capacities."
Germany is currently being hit by a heat wave with record temperatures.
With the exception of some coastal regions, the meteorological service (DWD) has warned of severe heat stress across the country.
"The forest is bone dry," said Jan Thomsen, spokesperson for the Berlin Senate's Department for Environment, Mobility, Consumer and Climate Protection.
Forests have not been able to recover from droughts in previous years, he explained.
