Hamas operatives on Monday shot and killed a Palestinian motorist who refused to stop at a roadblock they had set up in the southern Gaza Strip, witnesses said. Hamas gunmen said shots were fired first from the approaching car, and that they fired back. The incident took place near the southern Gaza town of Khan Younis. The identity of the dead man was not immediately known. There have been growing tensions between Hamas and the rival Fatah movement of Palestinian President Mahmoud Abbas in recent months, with gunmen from both groups often engaging in street clashes.