Medical officials said three Palestinians were killed. Islamic Jihad claimed one of them as a member. Residents said two of those killed were known gunmen in the city.
Residents said the third person was a civilian who happened to be passing by at the time of the shooting.
Hours later, medical officials said a 16-year-old Palestinian had been shot by Israeli troops near the West Bank hub city of Ramallah. The army said they opened fire on a group who threw stones and bottles at cars.
Ghassan al-Saadi, who said he witnessed the Jenin incident, said he saw Israeli snipers shoot at cars ahead of them. He said that when an ambulance arrived at the scene to rescue two people lying on the ground, the soldiers opened fire on them as well.
The Israeli army said it was not aware of such reports.