The rockets were fired about 75 minutes after the official end of the half-year truce between Israel and Hamas.
About two hours later, Palestinians opened fire at farmers working at the Kibbutz Nir Oz fields in the Eshkol Regional Council. There were no injuries, but several vehicles sustained damage.
The al-Quds Brigades, the Islamic Jihad's military wing, claimed responsibility for the rocket fire. The group said in a statement, the rockets were fired "in response to the enemy's crimes and the assassination of one of the organization's senior members in the Jenin area".
The organization said the rockets fired were of the Quds type and that the launching cell returned to its base unharmed.
Nicky Levy, deputy security officer at the Eshkol Regional Council, said that the council prepared for the renewed rocket fire before the truce expired.
"We woke up to the sound of the Color Red rocket alert system," said Yagil Avin, a secretary of one of the western Negev's regional councils.
"Several moments later, we heard two loud explosions. We are aware of the new situation created after the truce's expiry. Our alert and tension levels are up and we're more prepared."
He added, however, that "the escalation in the situation was felt several days ago. The coming days are critical and will determine where we're headed to."
'We're being held hostage at home again'
"The only thing left to do is to hope it lands far away and no one is injured," Dina Bernstein, a resident of one of the council's kibbutzim, told Ynet. Her house has yet to be fortified.
"Again we felt like we are being held hostage in our house – with no fortification, in an area exposed to hits. This gives you the feeling that only you can protect yourself, no one else, neither the government nor the army."
Earlier Friday, Hamas' military wing, the Izz al-Din al-Qassam Brigades, officially declared that the lull was over. The movement's spokesman announced on Thursday that the truce would not be renewed.
As the sides prepared for the post-lull era on Thursday night, a senior defense official told Ynet that Israel "will not accept a half-truce."
Security officials held several consultations during the day and formulated a policy whereby should Hamas and other Gaza terror groups refrain from firing at Israel, the IDF will also hold its fire, in effect creating an undeclared ceasefire.
However, officials made it clear that should Hamas and other groups continue to fire rockets and mortar shells at Israel, the IDF will weigh the use of gradual force, in a different format than it did before.
The senior security official told Ynet that the preparations for a new model of operations have been recently completed.
"The coming days will be days of longing on the part of Hamas, and days of wait for us," he said. "They will attempt to test us, and we will make it clear to them that it's not worth their while to continue."
Ilana Curiel, Shmulik Hadad and Ali Waked contributed to this report