ATHENS — Greece’s authorities on Wednesday launched an internal investigation into a deadly collision between a coast guard patrol vessel and a speedboat carrying migrants off the island of Chios.

According to a statement by the coast guard, the collision occurred after the speedboat, which had its navigation lights off, ignored signals from the patrol vessel and changed course. The boat capsized due to the force of the impact, sending its passengers into the sea.

At least 15 migrants were killed while 24 were rescued. A search and rescue operation is ongoing, and it is still unclear how many were on board. Two coast guard officers were also slightly injured.

A prosecutor ordered the arrest of a Moroccan national who was piloting the speedboat. The coast guard said a camera installed on its vessel was not active at the time of the crash.

An official from Frontex, the EU’s coastguard agency, said the agency wasn’t involved in the operation. Frontex has offered a plane to support the search and rescue but has not yet been asked by Greek authorities to deploy it.

Greece has repeatedly been condemned by the European Court of Human Rights, Frontex and the EU Commission for pushbacks of migrant vessels and for improper investigations by its coast guard. In the notorious case of the Pylos shipwreck, among the deadliest in modern Mediterranean history, an independent investigation by the Greek Ombudsman recommended that disciplinary charges be filed against coast guard officers for alleged dereliction of duty.

Migration Minister Thanos Plevris relayed the coast guard’s version of events and told the parliament that the tragedy underscores the fight Greece must wage against “killer smugglers.”

Dimitris Mantzos, spokesperson of the Pasok main opposition party, said: “The truth must be revealed institutionally, without ideological bias or anti-immigration rhetoric.”