I believe that the bombing was either the Irgun or possibly the Stern Gang, which used terrorism against British troops. The hagannah was more a militia.
The term Palestine was used by the Romans, after they destroyed the Temple and exiled the Jews in the first and second centuries AD. It is derived from Phillistines, the folks the early Israelites defeated under King David. It is a geographical term, and included everyone living in the area, whether Muslim Arab, Christian Arab, or Jew. Then the partition was derived to divide Palestinian Arabs, from Palestinian Jews. The leaders of the Palestinian Jews chose the name Israel for their state. The Palestinian Arabs refused to accept the partition, and insisted on sole control. Their leaders left the country, the neighboring Arabs attacked, Israel won.
Ping to above!