Tens of thousands of Palestinians, many of them Hamas supporters, attended a mass funeral procession in Gaza on Friday for de facto Interior Minister Said Siyam, who was assassinated in an Israeli airstrike on Thursday.

The funeral is also in honor of Siyam’s son Muhammad, his brother Iyad, his sister-in-law and her son, all of whom were killed in the same airstrike. The strike left a massive crater where Iyad Siyam’s house had stood.

A member of Hamas’ senior leadership, Siyam is the highest-ranking Palestinian figure to be killed in the current Israeli offensive.

Hamas hardliner turned Palestinian Martyr

Considered a hardliner within the Hamas movement, Siyam formed the Executive Forces, a parallel, Hamas-controlled security apparatus, after Hamas was elected to power in 2006.

While he took a hard line against Fatah in internal Palestinian politics, his assassination is likely to retroactively increase his stature among Palestinians of all political factions.

“Israel has a remarkable way of turning villains into heroes, into Gods,” said one Palestinian on Thursday, a resident of Bethlehem whose family is close to Fatah. He compared Siyam’s death to the assassination of Hamas’ wheelchair-bound spiritual leader, Ahmad Yasin, in 2004.

Born in 1959 in the squalor of Gaza’s Ash-Shati Refugee Camp, Siyam worked as a math and science teacher at local United Nations-run schools. He joined Hamas in the 1980s, one of its earliest members. Siyam quickly assumed leadership of the local teacher’s union.

He was active in the first Palestinian Intifada, or uprising, against the Israeli occupation, which began in late 1987.

Israeli forces jailed Siyam several times in the 1990s, and in 1992 exiled him for a year to southern Lebanon with hundreds of other Palestinians.

In the mid-1990s, Hamas’ rival, the Fatah movement of then-Palestinian leader Yasser Arafat, established the Palestinian Authority in the West Bank and Gaza, as part of interim peace deals with Israel. Siyam was jailed by Fatah-controlled PA security forces during this period.

He was elected to the Palestinian parliament in 2006, winning the most votes of any candidate.

As interior minister, Siyam had trouble controlling security forces that had been formed during Arafat’s rule, and were loyal to Fatah. It was then that he set up the Executive Force, which became the core of the Hamas police force in Gaza after the takeover of Gaza in June 2007.

After the takeover, Siyam’s forces established tight, if repressive control over the Gaza Strip, shutting down militias perceived to be loyal to Fatah.

On Thursday, Muhammad Nazzal a member of the Hamas political bureau, lamented the death of Siyam in as speech broadcast from Damascus.

Aluf Benn, an Israeli military correspondent, said Israeli intelligence confirmed the presence of Siyam and his staff near his brother’s home before ordering the assassination.

Hamas announced a period of mourning over the assassination of Syam, who was a member of the movement’s politburo, in addition to his role at the de facto Interior Ministry. Syam was appointed to the post shortly after Hamas won legislative elections in 2006.

Hamas condemned the killing of Syam’s son, brother Iyad and sister-in-law, as well as her son, who was killed along with four other neighbors near the home. Ten Palestinians were killed in the airstrike, including Syam and five of his family members.

Azzam