JERUSALEM — The Israeli government has in recent days been arresting young Jewish extremists suspected of being a part of a terrorist network that carried out a deadly attack against Palestinians, the national security agency Shin Bet said on Thursday.

The agency did not release names or any other details about the people who were arrested, or even how many there were, citing an official gag order imposed on the case. But it said that they were suspected of “belonging to a Jewish terrorist organization” and that there were “concrete suspicions” connecting them to an arson attack in July in the West Bank village of Duma that killed a Palestinian toddler and his parents.

The Israeli authorities determined early on that Jewish extremists were behind the attack, in which 18-month-old Ali Dawabsheh burned to death. His parents and older brother, Ahmad, who was 4 at the time, sustained critical burns over much of their bodies; the father died after a week, and the mother after five weeks. Ahmad is still being treated in an Israeli hospital.

Israeli leaders vehemently condemned the violence, but the investigation by the police and Shin Bet appeared to be making little or no progress for months. Many Palestinians have cited the unresolved case as one of the grievances in a buildup of popular anger against Israel and Israelis.

That anger has erupted over the last two months in a wave of violent attacks by Palestinians on Israelis. Most of those attacks appear to have been carried out almost spontaneously, by individuals with no known affiliation with militant organizations.

Four more attacks were reported on Thursday. A Palestinian gunman drove up to an Israeli military checkpoint in the West Bank and opened fire on the soldiers there, according to the military. The assailant was shot and killed, and one soldier and one bystander were wounded. Palestinian news outlets identified the gunman as an officer in the Palestinian Authority’s intelligence service.

Hours later, in Jerusalem, an Israeli police officer was stabbed by a Palestinian resident of the West Bank, the authorities said. A Palestinian doctor from a nearby clinic gave first aid. Police officers at the scene fatally shot the assailant. At night, a gunman fired at an Israeli vehicle near a West Bank settlement, causing no injuries. And two Palestinians stabbed a soldier in Hebron and were subsequently killed.

Critics have compared the slow pace of the Duma investigation with the swift arrest of Palestinian suspects in other recent deadly attacks, and something the Israeli defense minister, Moshe Yaalon, said in September raised further questions about the way the case was being handled.