Israeli troops left the Gaza Strip early Wednesday, hours after entering it in the most serious clash between the Israel Defence Force and Palestinian militants since a ceasefire went into effect June 19.
A military spokeswoman in Tel Aviv said the troops went into the Strip late Tuesday to destroy a 250-metre tunnel being dug under the border, which, she said, was being prepared to aid in the kidnapping of Israeli soldiers.
The operation was a "pinpoint" one, she said, to destroy an "immediate threat."
Unconfirmed Palestinian reports said at least five Hamas militants were killed in the Israeli operation, and the military spokeswoman said four soldiers were wounded.
Gazan militants responded to the Israeli operation by launching at least 35 missiles toward southern Israel Wednesday morning, the military spokeswoman said.

Shares fell 2.1 per cent Friday on the Seoul stock exchange on general recession fears. South Korea's won dropped against the dollar.
When the Spirit rover landed on Mars five years ago, no one expected it or its sister rover Opportunity to make it to their first birthdays, let alone their fifth.
Amelie Mauresmo fell victim to a leg injury after less than half an hour on court Friday to hand over a 4-0 victory which put French compatriot Marion Bartoli into the final of the Brisbane International.
Mumbai-based movie Slumdog Millionaire won five prizes Thursday night at the Critics Choice Awards, cementing its position as a surprise favourite just as the Oscar season moves into high gear.
After the Taipei Zoo received two giant pandas from China, another Taiwan zoo said Friday it is seeking to receive a pair of pandas from China.