JALAZOUN REFUGEE CAMP, West Bank — Palestinian youths clashed with Israeli forces while thousands of Israelis flocked to rallies, all of them protesting an arson attack that killed a Palestinian toddler — a rare instance of mutual shock in a land attuned to bitter violence.

Israel’s president implored the country to consider how the attack on Friday morning could have happened; Palestinians pointed to a widespread sense of impunity among Jewish extremists.

Such extremists were suspected to have firebombed a house in the West Bank hamlet of Duma, killing an 18-month-old boy, Ali Dawabsheh, and severely burning his parents and 4-year-old brother.

“A blatant disregard for the rule of law, for human dignity, for a love of mankind, for a love of Israel, and freedom of opinion has spread within us and is wreaking havoc,” President Reuven Rivlin of Israel said at a rally Saturday in Jerusalem.