Spain deployed its military to the Moroccan border Tuesday after thousands of Moroccans took advantage of their government's relaxed border controls to swim or paddle in inflatable boats onto European soil.

Live footage on Spain's public broadcaster TVE showed dramatic scenes of soldiers carrying children in their arms and Red Cross personnel helping migrants who were emerging from the water exhausted and cold. One unconscious woman laid on the sand before she was carried away from the beach on a stretcher.

The sudden influx of migrants has deepened the diplomatic spat between Rabat and Madrid and created a humanitarian crisis for Ceuta, the Spanish city of 85,000 that lies in North Africa on the Mediterranean, separated from Morocco by a double-wide, 10-meter (32-feet) fence.

A group of migrants walk wrapped in thermal blankets at a holding centre for migrants in the Spanish North African enclave of Melilla, Spain, Tuesday May 18, 2021. AP

Prime Minister Pedro Sanchez canceled a trip to Paris, where he was to attend a summit on international aid to Africa, to turn his focus to the crisis with Morocco.

By Tuesday morning, around 6,000 sea-soaked people had crossed the border into Ceuta since the first arrivals began early Monday, the Spanish government said, including 1,500 thought to be teenagers. The number getting in appeared to have slowed as Spain deployed additional police and soldiers to the border.

`It's such a strong invasion that we are not able to calculate the number of people that have entered,' said the president of Ceuta, an autonomous city of barely 20 square kilometers (7.7 square miles).

`The army is in the border in a deterrent role, but there are great quantities of people on the Moroccan side waiting to enter,' Juan Jesus Vivas told Cadena SER radio.

A group of migrants sit outside a holding centre for migrants the Spanish North African enclave of Melilla, Spain, Tuesday May 18, 2021.AP

One young man drowned Monday and dozens have been treated for hypothermia. The arriving adults were being transferred to Ceuta's main soccer stadium as they waited to be returned back to Morocco while those thought to be minors were sent to warehouses run by the Red Cross and other organizations.

Several military armored vehicles parked Tuesday at Tarajal beach in Ceuta, where the border fence leads to a short breakwater extending into the sea.

Morocco's loosened border watch came after Spain decided to allow the chief of a militant group that fights for the independence of Western Sahara into the country for medical treatment. Morocco annexed the sprawling region on the west coast of Africa in 1975.

Morocco's Foreign Ministry has said that Madrid's move to assist Brahim Ghali, head of the Polisario Front that has fought Morocco, was ``inconsistent with the spirit of partnership and good neighborliness'' and vowed there would be ``consequences.''

Vivas, Ceuta's conservative regional president, said residents were in a state of ``anguish, concern and fear.'' He linked the sudden mass arrival to Spain's decision to give compassionate assistance to Ghali.

The Spanish government itself, however, officially rejects the notion that Morocco is punishing Spain for a humanitarian move.

``I cannot envisage that putting the lives of young people and minors at risk is in response to a humanitarian issue, I simply cannot conceive it,'' Foreign Minister Arancha Gonzalez Laya said late Monday on the radio.

A man is taken on a stretcher by members of emergency team and Spanish Army in the border of Morocco and Spain, at the Spanish enclave of Ceuta, on Tuesday, May 18, 2021. AP

The prime minister's office said the government was supporting residents in Ceuta ``to ensure their safety and guarantee public order under any circumstances.''

`My priority at this time is to restore normalcy in Ceuta,' Sanchez wrote in a tweet. `Its citizens must know that they have the absolute support of the Government of Spain and the utmost firmness to ensure their safety and defend their integrity as part of the country.''

Interior Minister Fernando Grande-Marlaska added that authorities had processed the return of 1,600 migrants by Tuesday morning and that the rest would follow soon because Morocco and Spain signed an agreement three decades ago to return all those who swim into the territory.

Many African migrants regard Ceuta and nearby Melilla, also a Spanish territory, as a gateway into Europe. In 2020, 2,228 chose to cross into the two enclaves by sea or by land, often risking injuries or death. The year before the figure peaked at 7,899, according to Spain's Interior Ministry.

On Tuesday, another 80 Africans also crossed into Melilla, 350 kilometers (218 miles) east of Ceuta, by jumping over the enclave's double fence.

Morocco scored a diplomatic victory last year when the previous United States administration under Donald Trump recognized Rabat's sovereignty over the disputed Western Sahara to pave the way for normalizing relations between Israel and Morocco.

A man from Morocco is assisted by a Guardia Civil officer as he arrives swimming at the Spanish enclave of Ceuta, on Tuesday, May 18, 2021.AP

A man is helped by members of the Spanish Army as he arrives with others swimming at the Spanish enclave of Ceuta, on Tuesday, May 18, 2021. AP