The mass arrival by sea and land threatened a political crisis for Sanchez, a left-wing, pro-immigration leader who has clashed with President Donald Trump. Trump called the situation “terrible” on Friday.

The migrant crossings also fueled rapid alarm across Europe, where the continent’s divisions over immigration were laid bare.

France said it was increasing checks on its border with Spain, and Italy threatened to suspend Spain from the European Union’s internal open border scheme.

The rush was captured in images and videos that showed migrants swimming or floating on tubes from the Moroccan side on Thursday, and others breaking through a gate on land and running into the Spanish city.

Authorities on both sides of the Ceuta border appeared to be taking action to reinforce the fence separating Europe and Africa. Spain deployed its military along the coast and roads to control the crowds.

Most of those crossing appeared to be young men, but there were also families with women and small children.

Ahmed Karim, a 33-year old Moroccan, said he had crossed into Ceuta because of the lack of jobs in his country. “Many people want to go to Europe, America, but they don’t have the opportunity,” Karim said.