A series of Israeli strikes in the Gaza Strip on Tuesday killed three Islamic Jihad militant group leaders and 12 other people, with both sides bracing for an escalation.

Islamic Jihad vowed to "avenge" the deaths in a pre-dawn raid involving some 40 Israeli aircraft, with Israeli Prime Minister Benjamin Netanyahu warning "our enemies" to not "mess with us".

The first Israeli strike hit targets in the crowded coastal territory for nearly two hours from just after 2:00 am (2300 GMT Monday).

The Gaza health ministry said four children were among those killed and 20 people were wounded, with some in critical condition in the attacks which left buildings ablaze and reduced others to rubble.

The Israeli army said it had targeted three leaders of Islamic Jihad, which it considers a terrorist group, as well as its "weapon manufacturing sites".

Army spokesman Daniel Hagari expressed regret over the death of "uninvolved" people but said they were hard to avoid as "we are working against terrorists that conduct their activities day and night among civilians."

Islamic Jihad confirmed the deaths of three senior members -- Jihad Ghannam, Khalil al-Bahtini and Tareq Ezzedine -- before their bodies were later carried through the streets in mass funeral processions.

A separate air strike in the late afternoon on the city of Khan Yunis in southern Gaza killed two men in a car, the health ministry said.

(AFP)

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