15 people were slightly injured in the explosion of an ambulance in Bad Segeberg in Schleswig-Holstein.
The vehicle caught fire on Monday due to a technical defect, the police said.
During the fire brigade's work to extinguish the fire, there was an explosion in which twelve firefighters and three rescue workers were injured.
Oxygen bottles on board the ambulance may have triggered the explosion, a spokesman said. The force of the explosion also damaged three nearby cars, one of which was a total write-off. The police estimate the property damage at up to 300,000 euros.