Gaza, April 4 (IANS): Four Palestinians were injured early Friday in a series of Israeli airstrikes in the Hamas-ruled Gaza Strip, sources said.

The airstrikes came a few hours after Palestinian militants in Gaza fired four missiles into Israel, Xinhua reported citing local witnesses.

Israeli warplanes hit right after midnight a number of military sites in the seaside enclave that belong to Palestinian armed factions and Hamas police.

Medical sources said four people were injured in the attacks and have been hospitalised.

One of the targets was a metal workshop in the northern Gaza Strip town of Jabaliya, according witnesses.

Israel has not commented on the strikes. But Israeli media outlets reported that four missiles hit open areas in southern Israel.

This is the first round of violence since mid-March when Israel killed three Islamic Jihad militants in Gaza, prompting the Islamist group to fire a barrage of missiles into neighbouring Israeli communities.

In response to the rocket fire, Israel carried out several airstrikes that targeted military sites of the Islamic Jihad and Hamas movements.

The violence ended when Egypt restored a de-facto ceasefire it mediated in November 2012.