Roughly 8,000 migrants, an unprecedented influx at a time of high tension between Spain and Morocco, slipped into the Spanish enclave of Ceuta in northern Africa in two days, Spanish authorities said. They reached the enclave by swimming or by walking at low tide from beaches a few kilometers to the south, some using inflatable swimming rings and rubber dinghies.

Moroccan migrants climb a rocky cliffside as they attempt to cross the border from Morocco to Spain's enclave of Ceuta, in Fnideq, Morocco, May 18, 2021.

A migrant is comforted by a member of the Spanish Red Cross near the border of Morocco and Spain, at the Spanish enclave of Ceuta, May 18, 2021.

A Spanish civil guard waits for migrants to arrive at the Spanish enclave of Ceuta, near the border of Morocco and Spain, May 19, 2021.

Migrants arrive at the Spanish enclave of Ceuta, near the border of Morocco and Spain, May 19, 2021.

A man from Morocco is detained by soldiers of the Spanish Army at the border of Morocco and Spain, at the Spanish enclave of Ceuta, May 18, 2021.

Spanish Army and Guardia Civil officers take positions next to the border of Morocco and Spain, at the Spanish enclave of Ceuta, May 18, 2021.

A man lies on the ground after arriving in the Spanish territory at the border of Morocco and Spain, at the Spanish enclave of Ceuta, May 18, 2021.

Migrants rest after swimming towards the shore of the Spanish enclave of Ceuta, May 18, 2021.

A man is held by soldiers of the Spanish Army at the border of Morocco and Spain, at the Spanish enclave of Ceuta, May 18, 2021.

People mainly from Morocco stand on the shore as Spanish Army cordon off the area at the border of Morocco and Spain, at the Spanish enclave of Ceuta, May 18, 2021.

Spanish Army soldiers expel a migrant from the Spanish enclave of Ceuta, May 18, 2021.

A boy is helped by a man while climbing a fence in the area at the border of Morocco and Spain, outside the Spanish enclave of Ceuta, May 18, 2021.

Migrants climb a cliffside as they attempt to cross the border from Morocco to Spain's enclave of Ceuta, near Fnideq, Morocco, May 18, 2021.

Spanish Guardia Civil officers try to stop people from Morocco swimming and entering into the Spanish territory at the border of Morocco and Spain, at the Spanish enclave of Ceuta, May 17, 2021.

Minors sleep inside a warehouse turned into a makeshift center for migrant minors at the Spanish enclave of Ceuta, at the border of Morocco and Spain, May 19, 2021.

Spanish Army soldiers clash with migrants near the border of Morocco and Spain, at the Spanish enclave of Ceuta, May 18, 2021.

Moroccan migrants climb a rocky cliffside as they attempt to cross the border from Morocco to Spain's enclave of Ceuta, in Fnideq, Morocco, May 18, 2021.

Migrants stand on rocks as Spanish soldiers stand guard at the border fence of the Spanish enclave of Ceuta, May 18, 2021.

Spanish soldiers and police stand guard after a migrant crowd tried to cross the border between Morocco and the Spanish enclave of Ceuta in Fnideq, Morocoo, May 18, 2021.

Migrants avoid the Moroccan police as they try to reach the border between Morocco and the Spanish enclave of Ceuta, in Fnideq, Morocco, May 18, 2021.

A Moroccan citizen gets dressed after swimming at El Tarajal beach, near the fence between the Spanish-Moroccan border, after thousands of migrants have swum across this border during the last few days, Ceuta, Spain, May 18, 2021. (Reuters Photo)

Spanish soldiers stand guard as migrants stand on rocks off the shore of the Spanish enclave of Ceuta, May 18, 2021.

A Spanish legionnaire indicates the direction to follow to Moroccan citizens on El Tarajal beach, as they get out of the water on the Spanish side of the fence between the Spanish-Moroccan border, as thousands of Moroccans swim across this border Monday, Ceuta, Spain, May 18, 2021.

Migrants walk into shallow waters as they attempt to cross the border from Morocco to Spain's enclave of Ceuta, near Fnideq, Morocco, May 18, 2021.

A member of Red Cross helps a Moroccan citizen at El Tarajal beach, near the fence between the Spanish-Moroccan border, as thousands of migrants swam across this border during the last few days, Ceuta, Spain, May 18, 2021.

A man lies on the ground on the beach after swimming to the border area of Morocco and Spain, at the Spanish enclave of Ceuta, May 18, 2021.

Moroccan migrants walk on the shore as they attempt to cross the border from Morocco to Spain's North African enclave of Ceuta, near Fnideq, Morocco, May 18, 2021.