Medics said Samir al Khawaja, 29, was shot in the head when Israeli soldiers stationed along the Egyptian border opened fire on Palestinian houses.
In Ramallah, the commander of al Aqsa Brigades, was shot dead Tuesday night when an elite Israeli army unit stormed the neighborhood of Om el Sharayet.
A Thai worker was killed and two others injured earlier Tuesday when a mortar shell fired by Palestinian militants hit a greenhouse in the Gush Katif settlements block west of Kahn Younis in the southern Gaza Strip.
Al-Qassam Brigades, the military wing of Hamas, said in a statement its fighters attacked the settlements of Naveh Dikalim and Doghit with six mortars and two Qassam rockets.
Earlier Tuesday, Israeli forces entered a Palestinian refugee camp west of Khan Younis in southern Gaza, destroying several houses, security sources said.