Two men were arrested in connection with six armed robberies in south-east Madrid.
An inquiry was launched after two petrol stations were robbed at gunpoint in the Mejorada Del Campo and Loeches areas.
The raids were similar to four other petrol station robberies in surrounding areas and led to the arrest in Loeches, of a 30-year-old man suspected of being the ringleader.
A loaded firearm and clothes matching those seen on CCTV footage were found by arresting officers.
A 47-year-old man, suspected of being the getaway driver, was later arrested in the Rivas Vaciamadrid area.
Both men have previous records involving armed and violent robbery, police said.
The 30-year-old man has been denied bail and remanded in custody.