Spanish forces have captured six alleged pirates in the Indian Ocean, after the suspects attacked a Spanish navy ship.

The Spanish defense ministry says pirates aboard a skiff (small boat) opened fire on the combat support ship “Patiño” early Thursday.

A statement says the navy ship exchanged fire with the pirates, who eventually tried to flee on their boat. A military helicopter caught up with the pirates, who then surrendered.

The ministry says six suspected pirates were taken into custody, five of whom were injured. The detainees said a colleague who was killed during the incident had been thrown overboard.

The Spanish vessel is part of the European Union's mission to protect ships from pirates off the coast of Somalia and in the Indian Ocean.

Somali pirates have made hundreds of millions of dollars in ransom from hijacking ships in recent years.

Anti-piracy officials with the EU recently said pirates now receive an average of $4.7 million in ransom for each hijacking. However, the number of successful hijackings appears to be dropping, a trend authorities attribute to increased naval patrols and better security aboard the vessels.