Prime Minister Pedro Sánchez of Spain was set to arrive on Friday morning in Ceuta, a Spanish exclave in North Africa, a day after at least 18 people died as thousands of migrants surged into the territory from neighboring Morocco, leading Spain to mobilize its military, writes The New York Times.

The scenes at Ceuta`s border have set off a deep political crisis for Spain’s left-wing government. Mr. Sánchez was expected to address what his conservative opponents have called an invasion of Spanish territory after migrants crossed into Ceuta by climbing over border fences or swimming, sometimes for hours, to its shores.

A spokesman for Spain’s government said on Thursday that at least 18 people had died trying to reach Spanish soil.