Rafah, Gaza Strip  - Israeli aircraft bombed smuggling tunnels under the Gaza Strip-Sinai border early Tuesday morning, killing four Palestinians, Palestinian medical officials and the Israeli military said.

In addition, three other Palestinians were injured and three were missing after one of the tunnels collapsed over them, the head of Gaza emergency services, Mo'aweya Hassanein, told reporters.

Residents of Rafah, on the border with the Sinai peninsula, where most of the tunnels are located, said the Israeli aircraft dropped two heavy bombs on the border between the town and Egypt, targeting the underground tunnels. The casualties were working inside the tunnels at the time, they said.

Witnesses in the Egyptian part of Rafah told the German Press Agency dpa that the attack caused dozens of people to leave their houses near the border in panic and seek shelter in the nearby city of al-Arish.

A statement from the Israeli military said the airstrike was a response to a mortar attack Monday launched by militants from the Gaza Strip, which lightly injured one Israeli soldier.

Those mortars came after Israeli troops shot dead a Palestinian who failed to heed warnings to stop as he approached the heavily guarded border fence separating the Gaza Strip from Israel.

The incidents on Monday and Tuesday morning shattered a fragile calm which has prevailed in the Gaza Strip and surrounding areas since Israel ended its winter offensive against militants in the enclave, which had been launched in response to repeated rocket attacks.

Although rockets have still been sporadically launched, and the Israeli military has retaliated, the violence has been far from the levels of before the Israeli offensive. (dpa)