Nine Palestinians were slained during an Israeli military operation in the occupied West Bank, the worst in years, according to Palestinian officials, BBC News reported.
In the hotspot town of Jenin, a 60-year-old lady was reported deceased.
The Israeli military stated its forces moved in to capture Islamic Jihad members plotting "big assaults".
The Palestinian president accused Israel of a "massacre" in Jenin, the site of many operations in recent months.
The incursions are part of an anti-terrorism drive launched by the Israeli military in April.
On Thursday morning, heavy gunfire and explosions were be heard in video footage from the Jenin refugee camp, as Israeli forces encircled structures and engaged with Palestinian terrorists.
Magda Obaid, 60, Saeb Izreiqi, 24, and Izzidin Salahat, 26, were among those slain, according to the Palestinian health ministry. Twenty individuals were also injured, four of them critically, according to the report.
The Israel Defense Forces (IDF) stated its troops invaded Jenin to arrest an Islamic Jihad "terror squad", who it accused of being "heavily involved in planning and executing many major terrorist assaults on Israeli citizens and soldiers".
According to the report, officers surrounded a building and three armed suspects were "neutralised" after opening fire, while a fourth suspect surrendered. According to the IDF, troops were fired at by additional Palestinian militants and responded fire, striking targets. It claimed it was looking into "claims about more victims".
According to Islamic Jihad and Hamas, its militants attacked the forces with gunfire and improvised explosive devices.
The IDF stated the residence was being used as a hideaway by an Islamic Jihad cell, and furnishings inside had caught fire.
The exterior walls of the ground level were reduced to rubble, exposing the bathroom taps and sink. Meanwhile, the upper level was riddled with gunshot holes, and the stairs had a swimming pool.
Aisha Abu al-Naj, 73, who lives next door, told the BBC that the raid caused her and her children to seek shelter.
"We were afraid. I saw the army and then I couldn't open or look through the window. It was a scary situation," she was quoted by BBC in its report.
"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," she added.
According to the official Palestinian news agency Wafa, seven young people were shot and injured while attempting to block Israeli soldiers from entering Jenin, and the IDF "totally damaged" the Jenin Camp Club.
Taxi driver Mohammed Ammori claimed he was chatting to a buddy when Israeli military arrived in vehicles and a van near the club.
"We heard gunshots. We fled into the Jenin club and we stayed under siege there for three hours. After about an hour, military bulldozers destroyed cars on both sides of the road, then destroyed the club's wall," he stated, BBC reported.
According to Palestinian Health Minister Mai al-Kaila, Palestinian Red Crescent ambulances were initially unable to reach the injured due to Israeli forces limiting access to the location.
Israeli tear gas was also used at a nearby hospital's children's ward, she claimed. The IDF informed the AFP news agency that there was activity nearby and that tear gas might have entered through an open window.
In reaction to what his spokesperson described a "massacre" taking place "amidst world indifference," Palestinian President Mahmoud Abbas proclaimed three days of national mourning.
"This is what encourages the occupation government to commit massacres against our people in full view of the world," Nabil Abu Rudeineh was quoted by BBC in its report.
Jenin Deputy Governor Kamal Abu al-Rub informed AFP that people were living in a "true state of war" and that Israeli soldiers were "destroying everything and firing 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.
So far this year, Israeli troops have killed at least 29 Palestinians in the West Bank, including terrorists and civilians, as the military maintains operations there.
More than 150 Palestinians were slain in the West Bank last year, virtually all by Israeli troops. Unarmed bystanders, terrorist gunmen, and armed assailants were among those killed.
Meanwhile, a series of attacks on Israelis by Palestinians and Israeli Arabs, as well as militant firing at troops conducting arrest operations, killed more than 30 persons, including civilians, police, and soldiers.