MADRID (AP) — Thousands of migrants have streamed into the tiny Spanish territory of Ceuta in North Africa from Morocco, with at least 57 dying in the attempt, prompting Spain to deploy its military to restore the border.

Videos and images from the frontier showed crowds of people, mainly Moroccans, walking around the breakwaters at an urban beach near a border checkpoint with Morocco onto local roads. The majority looked to be young men, though there were also families with women and children. The escalation at the frontier comes after a surge in migrants attempting to reach the small exclave, mainly by swimming, a day before. It was not immediately clear what prompted so many people to cross to Ceuta. Spain’s government said it would send the Armed Forces to help the Civil Guard in Ceuta.Here’s what to know.

Thousands of migrants crossed into Ceuta from Morocco in recent days. Here’s what to know about the tiny Spanish territory at the center of Europe’s latest migration surge.

An autonomous Spanish city in continental AfricaCeuta and the larger Spanish territory of Melilla that is some 400 kilometers (250 miles) east, are located on the northern shores of the Mediterranean coast at the tip of Africa. Both autonomous cities belong to Spain and share the European Union’s only land borders with Africa.In Spanish possession since 1580, Ceuta is home to a mixed population of Christians and Muslims, and Spanish and Moroccan residents and day workers who live in relative harmony. Morocco does not officially recognize Ceuta and Melilla as Spanish territory, and often refers to them as occupied lands.