The Israel Defense Forces (IDF) said the strike had killed Zahi Yaser Abd al-Razeq Oufi, who it said had attempted a car bombing last month and supplied weapons.
It said he had been planning another attack imminently, and was killed along with several other Hamas operatives.
Wafa quoted a local official as saying children and elderly people from several families had been killed in the strike. There were also a large number of injured.
A local cafe owner and brother of one of those killed told Reuters news agency: “We are used to missile sounds, drones and the explosive drones, but the sound was strong.
“We haven’t heard this sound since 2002, during the second Palestinian uprising.”
Another witness, named as Abdallah Kanana, told the agency he was thrown from his chair as a result of the explosion.
The UN rights office condemned the attack in a statement on Friday.
“The strike is part of a highly concerning pattern of unlawful use of force by ISF (Israeli security forces) during military-like operations in the West Bank that have caused widespread harm to Palestinians and significant damage to buildings and infrastructure,” the UN said.
Tulkarm was one of the towns and Palestinian refugee camps targeted during a major Israeli military operation in August.
Last month UN rights chief Volker Turk said major Israeli operations in the occupied West Bank were taking place “at a scale not witnessed in the last two decades”.
Meanwhile, at least 24 Israelis including members of the security forces have been killed by Palestinian attackers in the same period, according to Israeli officials.
Read More: Israeli air strike kills 18 people in occupied West Bank