About 230 migrants have scaled a six-metre-high border fence to enter Spain's north African enclave of Melilla, local media report.
Three Spanish police officers and 18 of the migrants from sub-Saharan Africa were injured, Spanish state TV broadcaster RTVE reported.
Video footage posted by newspaper El Faro de Melilla showed people walking down a street as they shouted "victory, victory" and "asylum, asylum".
They were taken to an emergency reception centre and went into quarantine as a precaution against the coronavirus.
Spain has two autonomous towns in North Africa, both of which are claimed by Morocco: Ceuta on the Strait of Gibraltar and Melilla, 250 kilometres to the east.
Tens of thousands of people are waiting near Ceuta and Melilla for an opportunity to enter EU territory.
The biggest recent rush of migrants came in Ceuta in April, when Morocco opened the border and within a few hours 8000 migrants streamed in.
Most were quickly sent back.
Australian Associated Press