Israeli airstrikes have targeted the Gaza Strip's border with Egypt, as part of Israel's response to an attack on one of its frontier patrols on Tuesday.
An Israeli soldier was killed by an explosion on the Israeli side of the border. The air attack came after Israeli tanks and bulldozers had crossed into Gaza: Palestinian sources say there was heavy fighting near the town of Khan Younis.
Residents near the town of Rafah fled as missiles hit tunnels through which Israel says militants smuggle arms.
The strikes came ahead of United States envoy George Mitchell's visit to promote a permanent ceasefire between Israel and Palestinian group Hamas, which controls Gaza.
Both sides declared ceasefires earlier this month, ending Israel's three-week offensive on Gaza.
Israeli defence minister Ehud Barak has warned Palestinian militants that Israel will not tolerate any hostile actions.