Nine Palestinians have been killed during an Israeli military raid in the occupied West Bank, Palestinian health officials say - the deadliest in years.
An elderly woman was reported among the dead, in the flashpoint town of Jenin.
The Israeli military said its troops went in to arrest Islamic Jihad militants planning "major attacks".
The Palestinian presidency accused Israel of a "massacre" in Jenin, which has been the scene of repeated raids in recent months.
The incursions are part of what the Israeli military describes as an anti-terrorism offensive that began last April.
Heavy gunfire and explosions could be heard in video footage from Jenin refugee camp on Thursday morning, as Israeli troops surrounded buildings and clashed with Palestinian militants.
The Palestinian health ministry identified three of those killed as Magda Obaid, 60, Saeb Izreiqi, 24, and Izzidin Salahat, 26. Twenty people were also wounded, four of them seriously, it said.
The Israel Defense Forces (IDF) said its troops entered Jenin to arrest an Islamic Jihad "terror squad", who it accused of being "heavily involved in planning and executing multiple major terrorist attacks on Israeli civilians and soldiers".
It said forces surrounded a building and that three armed suspects were "neutralised" after they opened fire, while a fourth suspect surrendered. The IDF said troops were shot at by other Palestinian gunmen and returned fire, hitting targets. It added it was looking into "claims regarding additional casualties".
Islamic Jihad and Hamas said their militants had targeted the troops with gunfire and improvised explosive devices.
The BBC's Yolande Knell in Jenin reports that the house which the IDF said was being used as a hideout by the Islamic Jihad cell was still smouldering where furniture inside caught fire.
The outer walls on the ground floor were reduced to rubble, leaving the taps and sink of a bathroom exposed, our correspondent adds. The upper floor was meanwhile pocked with bullet holes, while the stairwell contained a pool of blood.
Aisha Abu al-Naj, 73, who lives next door, told the BBC that her house shook during the raid, forcing her and her children to take cover.
"We were afraid. I saw the army and then I couldn't open or look through the window. It was a scary situation," she said.
"There were some young Palestinians next to our building who then came and surrounded it. They shot at them. And then there was a lot of people who were killed."
The official Palestinian news agency Wafa reported that seven youths were shot and wounded while attempting to prevent the Israeli forces from entering Jenin, and that the troops "completely destroyed" the Jenin Camp Club.
Taxi driver Mohammed Ammori said he had been talking to a friend when Israeli troops pulled up beside a building close to the club in cars and a lorry.
"We heard gunshots. We fled into the Jenin club and we stayed under siege there for three hours."
He added: "After about an hour, military bulldozers destroyed cars on both sides of the road, then destroyed the club's wall."
Palestinian Health Minister Mai al-Kaila said Palestinian Red Crescent ambulances were initially unable to reach the wounded because Israeli troops restricted access to the scene.
The children's ward of a local hospital was also hit by Israeli tear gas, she said. The IDF told AFP news agency that there was activity not far away and that it was possible some tear gas entered through an open window.
Palestinian President Mahmoud Abbas declared three days of national mourning in response to what his spokesman called a "massacre" happening "amidst international silence".
"This is what encourages the occupation government to commit massacres against our people in full view of the world," Nabil Abu Rudeineh said.
Jenin Deputy Governor Kamal Abu al-Rub told AFP that residents were living in a "real state of war" and that Israeli forces were "destroying everything and shooting at everything that moves".
United Nations Middle East envoy Tor Wennesland said: "I am deeply alarmed and saddened by the continuing cycle of violence in the occupied West Bank."
"Since the beginning of this year, we are continuing to witness high levels of violence and other negative trends that characterized 2022. It is crucial to reduce tensions immediately and prevent more loss of life," he added.
At least 29 Palestinians have been killed by Israeli forces in the West Bank so far this year, including militants and civilians, as the military continues operations there.
Last year in the West Bank more than 150 Palestinians were killed, nearly all by Israeli forces. The dead included unarmed civilians, militant gunmen and armed attackers.
A series of Palestinian attacks targeting Israelis, as well as militant gunfire at troops during arrest raids, meanwhile killed more than 30 people including civilians, police and soldiers.
BDST: 2130 HRS, JAN 26, 2023