Israeli assault helicopters opened fire on the northern Gaza Strip late Thursday in response to Palestinian rocket attacks, a Palestinian security source said, as the two sides tested a fragile truce.
Israel's military response, which the army did not confirm, came after Palestinian militants fired five rockets at Israel earlier Thursday.
The action puts pressure on the new truce between the two sides that ended four days of violence.
A Grad rocket fired at the southern Israeli city of Ashdod from the Gaza Strip on Thursday evening was intercepted by the Iron Dome air defence system, media reported.
Two more rockets were fired at the same southern region during the night, after two had been fired there earlier in the day. None caused any casualties or damage.
The Israeli response in the north of the Gaza Strip late Thursday caused no injuries, the Palestinian security source said.
Israel and militants in Gaza agree to begin observing an Egyptian-brokered truce on Tuesday.
Israeli army spokeswoman Avital Leibovich told reporters that since the outbreak of the latest round of cross-border violence last Friday, Palestinians had fired 310 rockets at Israel of which "170 rockets or so" struck the Jewish state, several fell short inside Gaza and 60 were destroyed by Iron Dome.
A chain of Israeli air strikes and Palestinian rocket salvoes started when Israel killed Zuhair al-Qaisi, head of the radical Gaza-based Popular Resistance Committees, prompting other militant groups to fire rockets over the border.
The army said Qaisi had planned a deadly attack last August -- when militants sneaked across the border from the Sinai Peninsula and killed eight Israelis -- and accused him of planning a repeat attack "in the coming days."
Those ambushes on Israeli cars and buses took place on a southern section of Route 12, a lonely stretch of road running along the border between Israel's Negev desert and the Egyptian Sinai.
On Saturday, the army closed the road and Leibovich said it remained closed on Thursday, for fear an attack might go ahead despite Qaisi's death.
On Wednesday night, Israeli aircraft carried out two raids, one near Gaza City and another near the southern town of Khan Yunis, causing no casualties, Palestinian security officials said.
The Israeli military said the raids were in response to a rocket fired at Beersheva on Wednesday which was brought down by Iron Dome.
Many schools across southern Israel were again closed on Thursday as a safety precaution, after briefly reopening on Wednesday for the first time this week.
State-run television said that following Thursday's attempt to hit Beersheva, the city's schools would remain shut on Friday.
The Gaza-based militant group Islamic Jihad has weapons that can reach Tel Aviv, a member of the group's armed wing the Quds Brigades has told AFP in an interview.
The Quds Brigades fired most of the rockets that hit Israel in the past week's four-day conflict between Gaza militants and the Jewish state.
A member of the armed wing, who goes by the nom de guerre Abu Ibrahim, said the group was ready to expand the reach of its rocket fire beyond the Israeli town of Ashdod, which lies some 35 kilometres (20 miles) outside Gaza.
"If the occupation targets any leader of any Palestinian group whatsoever or any citizen, the Brigades will respond with force and expand the reach of the response beyond Ashdod," he told AFP.
"The enemy is aware of the range that the Brigades rockets can reach," he said, adding that the Quds Brigades possessed "many thousands" of rockets.
Abu Ibrahim said the group was receiving significant help from Lebanon's Hezbollah organisation, which he said provides "fundamental support" to the Quds Brigades, particularly by "facilitating the training of fighters."
Another Quds Brigades member, who spoke to AFP on condition of anonymity, said "certain resistance groups, including the Quds Brigades, have Fajr-3 and Fajr-5 missiles, with a range of 60-110 kilometres."
"But they are not for use unless Israel targets an important figure," he said.
He also claimed that Gaza militants possessed SAM-7 missiles which he said had been fired at Israeli helicopters last year.
Israeli Prime Minister Benjamin Netanyahu has warned the truce will be short-lived if the rocket fire continues.
He linked the rocket fire from Gaza to tensions with Iran over its nuclear programme, which much of the West believes masks a weapons drive.
"What's happening in Gaza is Iran. Where do the missiles come from? Iran. Where does the money come from? Iran. Who trains the terrorists? Iran. Who builds the infrastructure? Iran. And often who gives the orders? Iran.
"Gaza is an advance post for Iran," he said.
"I hope that the whole world today understands that the terrorist organisations in Gaza -- Hamas and Islamic Jihad -- and also Hezbollah in Lebanon, are sheltered by the Iranian umbrella.
"Can you imagine what would happen if that umbrella was nuclear?"
Under the terms of the truce, mediated by Egypt, both Israel and militants from Islamic Jihad, who were responsible for most of the rocket attacks, have agreed to hold their fire.