Between 1948 and 1956 there were many fedayeen attacks coming out of Gaza and many Israelis were killed. This was stopped only after the 1956 Suez War, when the UN sttationed an emergency force in the Gazaq Strip. But when Egyptian President, who ruled Gaza from 1948-1956, expelled the UN force in 1967, closed the Straits of Tiran and sent his forces into Sinai, then Israel conquered the Gaza Strip. After Israel unilatrerally left Gaza in 2005, the Gazans strted firing missiles at Israel and haven't stopped since.
Syria denies targeting refugee camp; UN condemns "murderous attack" (Reuters)
from the article: Two hurt in missile strike on bus carrying students near Gaza