Deadly Israeli airstrikes on Gaza following Hamas rocket fire
Israel's military said it had so far struck more than 20 militant sites in response to some 80 launches from the Hamas-run territory, reportedly rockets and mortars.
Missile defences had intercepted a number of the rockets, the military said on Monday but the renewed violence threatens to derail efforts to restore calm in the area, where a tentative ceasefire has been in motion.
The army said an Israeli bus was hit by fire from the Gaza Strip with medics reporting one person severely wounded by mortar shells.
Medics also said six people from the southern Israeli city of Sderot were lightly wounded, while a house in Netivot, another southern Israeli town, was also hit.
Gaza's health ministry said three Palestinians were killed in the Israeli strikes.
Militant group the Popular Front for the Liberation of Palestine (PFLP) claimed two of the dead were its members.
Hamas meanwhile claimed responsibility for the rocket fire on behalf of all Palestinian militant groups in Gaza, saying it was in revenge for a deadly Israeli military operation late Sunday.
"The joint command of Palestinian factions announce the beginning of bombardments of the enemy's settlements with scores of rockets," the Ezzedine al Qassam Brigades group said in a statement.
'Exchange of fire'
On Sunday, a clash erupted during an Israeli special forces operation in the Gaza Strip that killed seven Palestinian militants, including a local commander for Hamas' armed wing, and an Israeli army officer.
Hamas's armed wing, the Ezzedine al-Qassam Brigades, said the Israeli special forces team had infiltrated near Khan Younis in the southern Gaza Strip in a civilian car.
Al-Qassam agents stopped it and wanted to search it, realised it was an Israeli operation and confronted them, it said in a statement.
An exchange of fire followed in which local al-Qassam commander Nour Baraka was killed along with another militant, it said.
The car then attempted to flee and Israeli aircraft provided covering fire.
An Israeli helicopter landed near the fence and took away the special forces troops, according to al-Qassam.
Israeli military spokesman Jonathan Conricus declined to comment on the Al-Qassam account "because of the sensitive nature of the operation".
Israel provided few details on Sunday's operation, saying it was carried out by special forces and resulted in an "exchange of fire".Follow us on Twitter: @The_NewArab