The deceased are men in their 20s. One of them was shot dead while the other, who is an American citizen, is said to have been beaten to death.
The American man's family says in a statement that he was killed in connection with him defending the family's land against settlers "who tried to steal it".
The family demands in a statement that the US Department of State investigates the incident. They say that settlers prevented ambulance paramedics from helping the man, who died before he could be taken to hospital.
Israel's military says that stones were thrown at Israelis near Sinjil and that a "violent confrontation occurred in the area".
The US Department of State says that they are aware of the reports that an American citizen has died in the West Bank and refers "questions about an investigation to the Israeli government".
