Water-dropping planes from several European countries joined hundreds of firefighters Wednesday battling wildfires raging for days across Greece that left 20 people dead, while major blazes also burned in Spain’s Tenerife and in northwestern Turkey near the Greek border.

With firefighting forces stretched to the limit, Greece called for assistance from other European countries. Germany, Sweden, Croatia and Cyprus sent water-dropping aircraft, while Romania and the Czech Republic sent dozens of firefighters and water tanks.