Thousands of rockets were fired from Gaza towards Israel Saturday morning killing one Israeli as Jewish soldiers being taken hostage by militants from the Palestinian territory were reported on social media.

A statement released by the armed wing of Palestinian group Hamas, which rules Gaza, claimed responsibility for the attack involving the launch of more than 5,000 rockets.

"We decided to put an end to all the crimes of the occupation (Israel), their time for rampaging without being held accountable is over," Hamas said.

Rockets streamed across the sky repeatedly after the first launches from multiple locations across Gaza at 6:30 a.m., an Agence France-Presse journalist reported.

The Israeli army sounded sirens across the country's south and central areas, warning the public of incoming rockets and to stay near bomb shelters.

An AFP journalist in Jerusalem saw rockets being intercepted, moments after sirens blared across the city.

A woman in her 60s was killed "due to a direct hit" in Israel, the Magen David Adom emergency services said.

Fifteen others were hurt, two of them seriously, medics said.

The Israeli army also said Saturday that a "number of terrorists have infiltrated" Israel.

A resident of Be'eri settlement tells Israeli media that attackers are on the streets of the small town near the Gaza border, Al Jazeera reported.

Two Palestinian youths have been killed and five others wounded by Israeli forces' gunfire east of Bureij camp, in the central Gaza Strip, Al Jazeera said, citing local media reports.

CNN reports that Israel's military has declared a "state of war alert" and mobilizing troops.

Meanwhile, hundreds of Gazans flee homes from areas bordering Israel.

Israel launched air strikes in Gaza by Saturday evening, an AFP report said.

"Hamas has made a grave mistake this morning and launched a war against the State of Israel," Israel's Defense Minister Yoav Gallant said in a statement.

"IDF troops (Israeli army) are fighting against the enemy at every location," he said.

 WITH AFP