31 March 1937,
Elorrio and Durango were bombed by Francoist order. They were the first air strikes against the war civilians of 1936, by the Italian planes displaced from Soria. Until 26 April, Durango, which lacked protection from air strikes on many occasions, killed 336 people and seven flanders. They then went to Gernika.
Source:
Iñaki Egaña, The Crimes of Franco in Euskal Herria, 1936-1940. (Txalaparta)