An Israeli sniper killed a Palestinian policeman who was trying to extinguish a fire early Monday inside a compound at Bethlehem's Church of the Nativity, a Palestinian policeman holed up inside the church said.

The fire was apparently sparked by a stun grenade that Israeli troops tossed into the besieged compound, about 30 feet from the church, said the policeman, who only gave his first name, Salah. The church is built over the traditional birthplace of Jesus.

When 23-year-old Khaled Syam went to put out the fire, an Israeli soldier shot him in the head, Salah said.

The Israeli military said that it was investigating the reported incident and would not provide immediate comment.

Israeli troops stopped and searched a car full of Palestinian firefighters who came to extinguish the blaze. The firefighters were eventually allowed to go to Manger Square and put out the fire, but they weren't allowed to go inside the compound, Salah said.

Father Ibrahim Faltas, the superior of the Franciscan community in the church, said that he heard shooting and explosions, but he could not identify the source of the gunfire and blasts.

Israeli forces moved into Bethlehem shortly after they began their 11-day offensive in the West Bank, an operation that is targeting militant networks blamed for a series of suicide bombings in Israel.

Palestinian gunmen and clerics have been inside the church for a week. Israeli soldiers have been using loudspeakers to demand that the gunmen surrender, but they have refused to come out. The troops have been reluctant to storm the church. Any damage to the sacred site would cause an international uproar.