African migrants trying to reach Spain by boat hurled Molotov cocktails at a patrol vessel that tried to stop them — the first known attack in the drama of Africans risking their lives for a toehold in Europe.

The wooden boat was carrying 57 people, including two children, when a Spanish patrol boat intercepted it April 4 off the coast of Mauritania, police in the islands said Tuesday. Spanish vessels are stationed in Mauritania as part of a European drive to keep Africans from setting out on dangerous journeys to the Canary Islands.

When the patrol boat got close, some of those aboard the smaller vessel threw Molotov cocktails and other projectiles at the Spanish boat. No one was injured.

The Spanish Civil Guard police then dropped a Zodiac inflatable raft into the water and used it to try again to get close to the Africans and calm them down, but people on the boat tried to slash the raft with sharp objects, police said.

Authorities in the Canary Islands say this is the first time a patrol boat trying to detain people on the high seas came under attack in the decade since the Canary Islands became a destination for Africans trying to escape poverty and reach Europe's southern gateway.

Rather than open fire to stop the boat, the Spaniards gave up and let it continue on its route to the Canary Islands. It arrived Sunday on the southeast coast of the island of Gran Canaria and everybody on board was detained.

A Spanish Civil Guard officer who witnessed the attack was flown in from Mauritania to identify the assailants.

Normally, Africans who manage to reach the Canary Islands in such small overcrowded boats are kept in a holding camp for 40 days and eventually set free, but without residency papers or work permits, if the Spanish authorities cannot identify them.

This time Mauritania has agreed to take back the alleged assailants — their precise number is not known — right away for trial because the attack occurred in Mauritanian waters. The rest of the people on the boat will be allowed to stay in Spain.