Israeli police on Sunday arrested several people in connection with the deadly arson attack on July 31 which killed an 18-month-old baby and his father and severely wounded his mother and brother in the West Bank neighborhood of Duma.

Among those taken into custody were two well-known "ultranationalists," Meir Ettinger and Eviatar Slonim, who were arrested last week but on Sunday placed in "administrative detention," which allows suspects to be held without trial for up to six months. The controversial practice is often used against Palestinian detainees, but rarely against Israelis. Another suspected extremist, Mordechai Meyer, was placed in administrative detention last week.

An additional seven suspects were arrested Sunday after police raided settlements outposts in the West Bank.

The arrests follow growing pressure on Prime Minister Benjamin Netanyahu and his cabinet to crack down on growing far-right extremism in Israel. The firebombing and subsequent deaths of Saad Dawabsheh and 18-month-old Ali drew widespread condemnation around the world—and within Israel itself, a rare response by authorities to attacks on Palestinians.

Following the firebombing, Netanyahu said the Israeli government "will not countenance terrorism of any kind." According to Al Jazeera, the administration has also promised to allow "harsher interrogations of Israelis suspected of plotting violence against Palestinians with methods once reserved for Palestinian detainees."

Associated Press reports:

Israel's Shin Bet security agency has accused Ettinger of leading an extremist Jewish movement that encouraged attacks on Palestinian property and Christian holy sites, including an arson attack on a well-known church near the Sea of Galilee in northern Israel that marks the New Testament story of the miracle of the loaves and fish.

....Authorities said one of the raided outposts was Adei Ad, close to the Palestinian village of Duma, where the arson attack took place. In January, Jewish settlers near Adei Ad threw stones at U.S. consular vehicles carrying visiting American officials.

Authorities would not name the other outpost raided, but Israeli media identified it as Baladim. Both outposts — small, isolated Jewish settlements built without government authorization — are located in an area known for its hard-line settler population.

Thousands of people also held a funeral for Dawabsheh on Saturday, marching through Duma near the site of the attack. Dawabsheh's wife, Riham, and four-year-old son, Ahmad, remain in critical condition.