Israeli security forces shot dead three Palestinian gunmen in the occupied West Bank on Sunday, Israeli police said in a statement.
The statement said special forces "thwarted a squad from the Jenin refugee camp that was on its way to carry out an attack".
Hazem Qassem, a Hamas Gaza spokesman, said the deaths would not go unpunished.
"The enemy, which assassinated three of our Palestinian people, will not escape paying the price of its crimes," he said in a statement.
The Israeli police statement said the head of an armed squad who was "involved in military action against Israeli security forces and advancing military activity directed by terrorists in the Gaza Strip," had been killed along with two other squad members.