GAZA CITY - Two Palestinian teenagers died in an Israeli air strike on central Gaza on Tuesday, prompting a rare bout of rocket fire from the military wing of the ruling Hamas movement.
The two raised to six the total number of Palestinians killed in a series of Israeli strikes on Gaza since Monday, all carried out just hours after a deadly ambush along Israel's southern border with Egypt.
Israel has said the sudden spike -- three deadly air raids in just over 12 hours -- was "in no way related" to the border incident, with the military saying the air force targeted militants planning or engaged in anti-Israeli attacks.
The latest strike which killed two 17-year-old youths took place shortly after midnight near Deir al-Balah, but their bodies were only recovered after dawn "when an ambulance could get to the scene," medics told AFP.
Hospital staff named the pair as Mohammed Bassem Abu Mealiq and Yusef al-Talbani. Witnesses said they had been trying to breach the fence bordering Israel when they were hit.
Initial reports spoke of two injured in the strike but it later transpired that they were dead.
The military said it had targeted "a terrorist squad handling an explosive device" near the security fence in central Gaza.
Several hours later, four rockets were fired into southern Israel's Hof Ashkelon district in an attack claimed by Hamas's military wing, the Ezzedine al-Qassam Brigades, which said it was in response to "Israel's crimes."
Such fire by the group, which generally maintains a tacit truce with Israel, is very rare.
On Monday, another four Palestinians were killed in two Israeli sorties over Beit Hanun in northern Gaza that also wounded three other people, medics said.
One of those killed was identified by the Qassam Brigades as one of its militants: 23-year-old Jihad Abu Shbab. The second victim, Mohammed al-Zaanin, 25, was not affiliated with any armed faction.
Israel said it had targeted "a terrorist squad attempting to fire a rocket at Israel."
Earlier in the day, another strike targeted a motorcycle east of Beit Hanun, killing two Islamic Jihad activists in their 20s, Mohammed Shabat and Ismail Odeh, medics and witnesses said.
The military said they were part of a "squad of snipers operating near the security fence in the northern Gaza Strip" that had fired at an Israeli farmer working near the fence last Thursday.
Figures quoted on Monday morning by the military indicated that since the start of 2012, Gaza militants had shot off 282 rockets into Israel, 10 of which were fired this month.
Since then, another six rockets have hit Israel, an army spokeswoman said on Tuesday morning.
The last major flareup in Gaza was in March when four days of tit-for-tat violence left 26 Palestinians dead, and saw militants firing more than 200 rockets into Israel.
The fighting erupted when Israel assassinated a militant leader from the Popular Resistance Committees who it said was responsible for planning an attack along Israel's southern border with Egypt in August 2011 in which gunmen sneaked over the frontier and killed eight Israelis.
Within hours, Israel hit back at Gaza, sparking eight days of bloodshed that left 26 Palestinians and an Israeli dead.
Monday's border attack raised fears Israel would once again hold Gaza militants responsible, although there was no such claim in the immediate aftermath of the incident in which an Israeli civilian and two gunmen died.
Asked about the possible involvement of groups from Gaza, Israeli military spokeswoman Avital Leibovich said: "There is speculation about that. Intelligence is checking right now."