Two worshippers and three security guards are dead after an attack on the island of Djerba, where 5000 Jews had gathered for an annual pilgrimage.

Two worshipers were killed when a Tunisian naval officer opened fire at a synagogue on the island of Djerba on Tuesday night, as hundreds of Jews held an annual pilgrimage there.

The pilgrims who died were cousins Aviel and Benjamin Haddad, who lived in Israel and France respectively.

Three guards were also killed in the attack on the heavily secured El Ghriba synagogue, including one who died hours after the attack. Nine other people, including four civilians, were injured, the Tunisian Interior Ministry said on Wednesday.

The gunman, a naval officer, was shot dead by other guards after the attack.

According to the ministry, the officer, affiliated with the National Guard naval centre in the town of Aghir on Djerba, first turned his service weapon on a colleague, then grabbed more ammunition and made his way to the synagogue.

When he reached the area, he began shooting wildly at security units stationed at the synagogue, who responded with gunfire, killing him. The synagogue was locked down and those inside were kept secure, the ministry said.

Authorities are probing what led to the attack. Some analysts have floated the possibility that it was a response to this week’s events in Gaza, but the Tunisian Ministry refrained from referring to it as a terrorist attack and said investigations were continuing.

The permanent Jewish population of Djerba has dwindled to about 1000 but the annual Lag B’Omer pilgrimage to the El Ghriba attracts thousands of visitors each year.

Tradition holds that the pilgrimage marks the finding of the long ago found the body of a girl who lived and died alone — but whose body was miraculously preserved.