An Israeli air strike in the Gaza Strip Thursday killed two Islamic Jihad militants and wounded another, bringing to four the number of group members killed by Israel in less than 24 hours and drawing a vow of revenge.

Islamic Jihad says the three men were returning together to their homes in the Mughazi refugee camp in central Gaza after a night spent on patrol along the Gaza-Israel border when they were targeted.

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The Israeli military said an aircraft attacked the three armed men after they fired an anti-tank missile at troops on the Israeli side of the border fence. No soldiers were reported injured.

An Israeli airstrike Wednesday evening killed two members of the same organization.

The Israeli military said the target in that raid was a senior Islamic Jihad militant who was involved in firing rockets at the Israeli city of Ashkelon, north of Gaza.

Islamic Jihad official Abu Ahmed vowed Thursday morning that his group would avenge the killings.

"Our rockets and our resistance will not stop," he said. "We know where and when we will take revenge for these crimes."

A short time later, a rocket fired from the northern Gaza strip landed in empty ground in southern Israel, the military said. There were no reports of casualties and it was not immediately clear if the incidents were related.