Eighteen Palestinians have been killed in an Israeli raid on the Jenin refugee camp in the occupied West Bank, the Palestinian health ministry says.
It said at least 20 others were injured in the assault, which residents said involved two drone strikes.
It is one of the deadliest recent incidents of its kind in Jenin, which has been repeatedly raided by Israel as part of a drive against militants.
The Israeli military said it had sent in undercover units to arrest suspects.
The Israel Defense Forces (IDF) launched an assault on the camp overnight, using armoured bulldozers to destroy homemade bombs. Troops came under fire and a drone was used to attack a group of gunmen, the IDF said. The bulldozers ripped up the already badly damaged streets.
The IDF said troops re-entered the camp hours later, coming under renewed gunfire. Another drone was used to attack gunmen again, it said.
During the clashes, the air force reportedly dropped leaflets telling residents: "The IDF remains here and will return again and again until terrorism is completely eradicated. Stay away from terrorism, live in peace," the Jerusalem Post newspaper reported.
The Israeli military has been carrying out near nightly arrest raids across the West Bank for a year and a half, following a wave of deadly attacks by Palestinians which killed more than 30 Israelis.
According to the UN, this year more than 400 Palestinians - both militants and civilians - have been killed by Israeli forces or settlers in the West Bank, making it the deadliest there since the UN began recording Palestinian fatalities in 2005.
A number of Palestinian attackers have come from Jenin, which has become a major base for Palestinian militants in the West Bank.
Israeli-Palestinian tensions in the West Bank, which were already high, have been fuelled further by the war in Gaza, which began after an unprecedented deadly attack on Israel by Hamas gunmen on 7 October. More than 150 Palestinians and three Israelis have been killed in the West Bank since the war began.