One of the masterminds behind the abduction of Israel Defense Forces soldier Gilad Shalit was among four militants killed by IDF troops in the Gaza Strip on Wedmesday, Hamas sources told the Palestinian news agency Ramatan.Palestinian witnesses said troops killed at least four militants in separate incidents in the Gaza Strip before dawn Wednesday. IDF sources confirmed the deaths of two militants in southern Gaza. The army pushed further into the southern Strip along the Philadelphi Route on Tuesday for the first time since since the disengagement over a year ago. IDF sources said Wednesday that the army has plans to expand the operation. An IDF spokesman confirmed that troops killed two men as they approached army positions in Rafah, on Gaza's border with Egypt, an IDF spokesman said.