Israel has sealed the Gaza Strip, a day after a Palestinian suicide bomber blew herself up at a border crossing.

Israel closed the crossings between the Gaza Strip and Israel, preventing thousands of Palestinians from reaching their jobs. The closure is in response to a suicide bombing that killed three Israeli soldiers and a civilian security guard Wednesday.

Immediately after the bombing, the military announced a closure that has been extended indefinitely. An army statement said the Erez Industrial Park on the border is also closed. About 6,000 Palestinians work there.

The army said that only humanitarian cases would be allowed to cross the border. Gaza merchants have also been banned from taking produce into Israel.

The statement did not say how long the measures would remain in effect. Israeli Prime Minister Ariel Sharon's deputy said a military response should be expected. Deputy Prime Minister Ehud Olmert told Israel Radio, "if it requires striking at those planning or setting in motion acts of murder, then we have not refrained from doing so in the past and shall not refrain now."

Brigadier General Gadi Shamni, the Israeli military commander in Gaza, also indicated Israel would retaliate for the attack. He told Israel television Israel will know how to respond at the time, place and method of its choosing.

The attack Wednesday was the first time the Islamic militant group Hamas sent a woman on a suicide mission, and signaled a new tactic in circumventing Israeli security checks that focus mainly on Palestinian men.

In a videotaped message before the attack, the 21-year-old mother of two said she wanted to turn her body into deadly shrapnel. Israeli soldiers handed her remains over to Palestinians in Gaza in two white sacks.