More than 200 migrants from sub-Saharan Africa managed to cross the high fence that marks the border between Melilla and Morocco on Thursday morning and entered the Spanish enclave.
The Spanish authorities said this was one of the largest arrivals in recent years.
In total, shortly before 7 am, more than 300 people tried to climb the triple metal fence using hooks, and 238 men managed to enter Spain.
Local media footage of Onda Sero allegedly shows migrants rejoicing in the streets after successfully entering the enclave.
Three policies received minor injuries and the migrants were transferred to a residence center, where they will remain in quarantine due to health conditions, the Melilla prefecture said in a statement.
The invasion came just over two months after an unprecedented wave of migration in another Spanish enclave in northern Morocco, Ceuta, which was overrun in mid-May by the sudden arrival of more than 10,000 migrants, the vast majority of whom were Moroccan youth and adolescents.
This exceptional wave of migration took place in the context of a major diplomatic crisis between Madrid and Rabat, caused by the admission in Spain of the leader of the Saharan independence movement Frente Polisario Brahim Gali, Rabat’s nemesis, for treatment.
Gali left Spain in early June for Algeria, but relations between Madrid and Rabat remain tense.
Melilla and Ceuta, the only land borders of the European Union with Africa, have experienced strong migration pressures for many years.