Islamic Jihad's military wing, the al-Quds Brigades, promised Israel that "the terror of rockets would continue to haunt residents of Sderot and the Gaza vicinity." The group claimed responsibility for two Friday night rockets that landed in the western Negev.
The Israeli military said three more rockets were fired Friday morning and that troops guarding Israeli farmers in fields adjoining Gaza also came under sniper fire from across the border.
The Islamic Jihad said that the rockers were "in response to the crime of occupation in Gaza and the West Bank, and were intended to let the Zionist occupiers know that our missiles and rockets will continue to plague them."
Hundreds of IJ members gathered at a rally, calling for a complete rejection of any additional ceasefires. Spokesmen for the organization declared that the "resistance was unstoppable" and that "jihad and resistance were the only way."
Hamas echoed such sentiments in a statement posted on its Web site, announced its intention to maintain steadfast in choosing 'resistance' over a renewed ceasefire.
"Since the enemy did not abide with the conditions ... we hold the enemy the fully responsible for ending the truce and we confirm that the Palestinian resistance factions headed by Hamas will act," the statement said.
In Washington, Secretary of State Condoleezza Rice was critical of Hamas' move.
"I sincerely hope that there will not be a resumption of the violence because that is not going to help the people of Gaza, it is not going to help the Palestinians, it is not going to help the Palestinian cause," she said.
Israeli soldiers entered Gaza to destroy a tunnel that the army said could have been used in a cross-border raid. In response, Palestinian militants resumed firing rockets at Israel.
On Thursday, Gaza militants fired 11 rockets and six mortar shells toward Israel and Israel staged at least two airstrikes against rocket squads. The day before, at least 20 rockets were fired at Israel, wounding two people and causing property damage, the army and police said.
Associated Press contributed to this report