CEUTA, Spain — Spain installed a 500-meter-long (1,600-foot) barrier on the sea border between its North African territory of Ceuta and neighboring Morocco on Saturday, after tens of thousands of migrants breached the frontier earlier in the week in one of the deadliest mass crossings in recent memory.

At least 67 migrants died, including some who drowned and others killed in a stampede while attempting to cross a breakwater barrier, the Spanish government said Saturday. The sudden arrival of 50,000 to 60,000 migrants on Thursday and Friday — an enormous influx for a city of roughly 85,000 residents — triggered a humanitarian crisis and reignited the immigration debate across Europe and beyond, although most of the migrants returned to Morocco shortly afterward.

The image of crowds storming into Ceuta — a Spanish possession since 1580, situated on the Strait of Gibraltar at the entrance to the Mediterranean Sea — was seized upon by critics of Spain's socialist government, particularly right-wing and far-right politicians. Spain's migration policy has centered on granting legal status to unauthorized workers who entered the country before 2026 in order to bolster the economy, a sharp contrast to the anti-migration and pro-deportation stance adopted across much of the EU and in the United States.

Spanish Prime Minister Pedro Sánchez criticized the reaction of some EU leaders to the events in Ceuta, stating that calls for Spain to be suspended from the EU's borderless Schengen zone were "driven by prejudice, fake news, ignorance, or political interest." Despite the crisis, Spain has recorded fewer illegal migrant crossings in recent years than its Mediterranean neighbors Italy and Greece.

On Saturday morning, a small number of migrants who swam to Ceuta's urban Tarajal beach were met by soldiers who escorted them across the border.

"We are relentless against those who break the law," Spanish Interior Minister Fernando Grande-Marlaska told journalists.

Asked how the breach could have occurred given the heavy security on both sides of the border, and whether Morocco posed a threat to Ceuta, Marlaska defended the government in Rabat.

"The events require an evaluation by Spain and Morocco," he said, adding that cooperation with its neighbors had enabled Spain "to revert the situation in 24 hours."

"Morocco is not a threat to Ceuta, or to the rest of Spain. It is a reliable partner," Marlaska said.

EU Leaders Call for Coordinated Response

Other European Union countries called for urgent talks and a coordinated response to the situation in Ceuta.

"We cannot allow uncontrolled mass crossings, the instrumentalization of migration or other hybrid threats to create the perception that illegal entry into the European Union is possible. That a migrant's illegal entry can turn into legal stay," a letter to top EU officials, released Saturday by the Danish prime minister's office, stated. "Such a perception would encourage further attempts, undermine confidence in our common migration policy and have repercussions for all Member States."

Leaders of Italy, Denmark, Austria, Belgium, Bulgaria, Cyprus, Croatia, the Czech Republic, Estonia, Finland, Germany, Greece, Hungary, Latvia, Lithuania, Malta, the Netherlands, Poland, Romania, Slovenia, Slovakia, and Sweden signed the letter, asking the EU's current Irish presidency to convene a videoconference of interior ministers. Ceuta, along with Spain's other North African exclave Melilla, constitutes the European Union's only land borders on the African continent, giving the crisis implications well beyond Spain's bilateral relationship with Morocco.

Sánchez also requested a videoconference of EU interior ministers to "enable us to establish a common response to situations of this kind and reaffirm that the security of our external borders is a shared responsibility of all Member States, and not only of those on the Union's front line."

Italy threatened to suspend the open-border Schengen agreement with Spain and was reimposing border controls for people arriving from Spain by air and sea. However, Ceuta is not part of the Schengen area, and border checks are conducted when traveling from the exclave to continental Spain or other Schengen-zone countries.

"In the current international context, the European Union cannot afford this kind of selfish, polarizing and unlawful reaction," Sánchez wrote in his letter.

Migrants Head Back into Morocco

Hundreds of migrants continued making their way back to Morocco on Saturday. Hungry and angry, some barefoot or shirtless and others nursing visible injuries, they said they were leaving Ceuta after what they described as degrading treatment on the Spanish side of the border.

Migrants walked along a long stretch of wave breakers before slipping into Morocco through a small breach in the border fence. Most were Moroccans, with a smaller number from sub-Saharan Africa.

"I decided to come back on my own," said Ouail Lamzeiz. "I spent eight days in Ceuta, and I was about to get a bed at the migrant center, but I hadn't eaten for days. Even the Moroccans there didn't help," he added, displaying a document supporting his account.

Migrants said they spent nights sleeping in forests around Ceuta because they could not find shelter, and that fights over food were frequent.

Othmane El Merzoug asked passersby for a phone call so he could contact his family and ask them to send money for the journey back to his hometown, approximately 189 miles (305 kilometers) from the border.

Life Along the Border Disrupted

Along Ceuta's Tarajal beach, sunbathers largely ignored the streams of migrants walking toward the border.

Ceuta resident Mohamed Abdelatif, 21, said the border rush had ruptured the city's peace.

"The reality is, it's not good," Abdelatif said, before wading into the water with his girlfriend.

To reach Ceuta, on the northern African coast, migrants often swim from the Moroccan town of Fnideq, covering about 3 miles (5 kilometers) to reach Spanish territory. In response to the influx, Spain deployed its armed forces and additional police to Ceuta. On the Moroccan side, security forces clashed with migrants, deploying water cannons, tear gas, and warning shots in an effort to turn them back.

On Saturday, the road linking Fnideq to the border crossing bore the scars of the unrest. Burned-out vehicles sat along the roadside, and the acrid smell of smoke lingered in the air. Water cannons remained stationed nearby.

"Life in this city has been disrupted as a result of the border incident," said Ceuta President Juan Jesús Vivas. "The return of people has begun satisfactorily, but the process must be completed."

Some Migrants Determined to Stay

Some who reached Ceuta said they had no intention of returning. Among them was Mohamed Hatri, a 23-year-old Moroccan.

"They've closed everything down so that we can't buy anything to eat, to force us to return to our country," he said, adding that he and others were determined to stay "whether we're hungry or not."

Ceuta residents also demonstrated against the arrival of Spanish far-right politician Alvise Pérez in the enclave on August 1.

— Oubachir reported from Fnideq, Morocco. Renata Brito in Barcelona, Spain, and Elena Becatoros in Athens, Greece, contributed to this report.