According to witnesses and Palestinian health officials, an Israeli military raid in the occupied West Bank resulted in the deaths of nine Palestinians, including an elderly man and several militants.
As soldiers raided the center of Nablus, gunmen came under fire and there were explosions and gunfire.
It is believed that two senior Palestinian militants were killed inside a house after receiving heavy Israeli fire.
The Israeli military had earlier announced that it had troops present in Nablus.
A 72-year-old civilian was reportedly among those killed outside a besieged house, during the gunfights, according to Palestinian health officials.
In what is typically a bustling market area of the old city, video footage revealed a body next to bags of bread in a street.
According to the health officials, more than 100 people were also injured by gunfire, six of whom required serious medical attention.
In response to a wave of lethal Palestinian attacks over the past year, Israel has increased its search, arrest, and intelligence gathering operations in Nablus and the nearby Jenin area.
This latest one occurs in spite of reports this week that the US had mediated a deal to reduce tensions.
At least 50 Palestinians have died this year so far, including militants and civilians, while 11 Israelis have died as a result of Palestinian attacks.