A French Moroccan national has died and another was detained by Algerian authorities after an incident off the coast of Algeria, according to a French diplomatic source.

A family member who says he witnessed the incident told local Moroccan media that two men had been shot dead Tuesday by Algerian authorities and one was arrested.

The family member told private Moroccan news outlet Le360 Thursday that he was among four men who had got lost on jet skis in Algerian waters while holidaying at a resort in Morocco, when Algerian security forces allegedly fired on them. The border between the two countries has been closed for decades.

Bilal Kaisi, 29, and Abdelali Meshawer, 40, were killed in the incident, while Ismail Snaby was arrested by the Algerian coast guard, the brother of Kaisi, Mohamed Kaisi, told Le360.

Mohamed Kaisi was found in the water by the Moroccan security forces after the incident, he told local media.

A funeral was held for Kaisi, whose body was found by a local fisherman the next day. Meshawer's body has yet to be found, Le360 said.

The French diplomatic source did not elaborate further on the incident but said it involved other French nationals. The source added that French authorities are in contact with the families of those affected and in communication with Moroccan and Algerian authorities.

Moroccan media said both men killed are French Moroccan.

CNN has reached out to the Algerian foreign ministry.

When asked about Tuesday's incident, Morocco's government spokesperson told a local news conference that the case would "usually" be part of "judicial authority's jurisdiction" but did not comment further.

The neighboring nations have long had a hostile relationship over Morocco's claim on the Western Sahara and Algeria's support for the Polisario Front -- an armed group seeking independence of the region.

Algeria broke off diplomatic relations with Morocco in 2021; the shared border between the countries has been tightly closed since 1994.