Two courageous petrol station employees have overpowered a gunman suspected of killing two elderly victims in drive-by shootings in southern Germany, officials say.

The two workers stepped on Friday in when the suspect pulled over at a petrol station after allegedly gunning down an 82-year-old woman followed later by a male cyclist, 72, they said.

The shooter had driven and fired at his victims from a silver Mercedes convertible, in Leutershausen in northern Bavaria, sparking a public alert and major police hunt, including by helicopter.

The suspect then went on to fire at a farmer on his tractor, who was wounded by fragments, before driving another 30km, before stopping at the petrol station and being overpowered by the two heroic employees.

Bavarian Interior Minister Joachim Herrmann praised the ‘courageous intervention’ by the petrol station workers.

The 47-year-old suspect was arrested by police, who said there was no immediate suggestion he had any connection to the victims. His motive remained unclear.

After his detention, he displayed ‘psychological abnormalities’ and was to be initially assessed by an expert, the chief prosecutor in the city of Ansbach, Gerhard Neuhof, told reporters.

The mayor of Leutershausen, Siegfried Hess, said he was ‘stunned’ and told national news agency DPA: ‘In a place with 5500 inhabitants where we have always had a quiet life, we only know this kind of situation from television.’