At least 18 people were killed at the Tulkarm refugee camp in West Bank following an Israeli airstrike, said the Palestinian Health Ministry.
The Israeli military says the strike killed a local Hamas leader, Zahi Yaser Abd al-Razeq Oufi.
It accused Oufi of participating in numerous attacks in West Bank and said he was in the process of planning another assault.
The air raid was the deadliest in the West Bank since 2000, the AFP news agency quoted a Palestinian official as saying.
The Palestinian movement Fatah, a Hamas rival based in West Bank, called for demonstrations on Friday to honor the "heroic martyrs" of Tulkarm.
Tulkarm was one of the towns and Palestinian refugee camps targeted during a large-scale Israeli military operation in late August against militants based in the West Bank.
Violence in the territory has surged alongside the war in Gaza which began after Hamas, which is designated as a terrorist organization by a number of countries, attacked Israel on October 7.