(Updates with Israeli army comment, paragraphs 2,7)
By Nidal al-Mughrabi
GAZA, Jan 7 (Reuters) - Israel launched a series of air strikes on the Gaza Strip on Thursday, killing at least one Palestinian and wounding another, medical workers and the Islamist group Hamas said.
The Israeli army said it had launched four raids after a dozen mortar bombs and a rocket fired from the territory struck the Jewish state, where no injuries were reported.
Explosions rocked Gaza City, Khan Younis and Rafah, which is on the Egyptian border, sending flames shooting into the air.
Israel's first strike of the evening was its first inside the crowded city of Gaza since a three-week offensive a year ago in which 1,400 Palestinians and 13 Israelis were killed.
One Palestinian died and another was hurt on Thursday in the latest Israeli raid on a tunnel beneath Gaza's border with Egypt, and several other people were feared trapped inside the ruins, medics said.
Israel says the tunnels are used to smuggle weapons from Egypt, while Palestinians say they need them to bring in staple supplies due to an Israeli blockade of the coastal Gaza territory.
An Israeli military spokeswoman said Israel had targeted a weapons factory in Gaza City and three tunnels, including one dug near its border which it suspected was intended to allow a cross-border incursion by militants. The other two were next the Gaza Strip's border with Egypt.
Hamas, a militant group that rules Gaza, said an Israeli warplane bombed a building in Gaza City that witnesses said appeared to belong to the Islamic Jihad militant group. Militants barred reporters from reaching the area.
Israel also fired missiles at targets in Khan Younis, a town in southern Gaza. One of them struck an uninhabited area near a school, causing no injury, witnesses and medics said.
A further air strike targeted a zone in southern Gaza where militants of the Popular Resistance Committees fire mortars at Israel. The group claimed responsibility for shooting at Israel earlier, striking two days after Israel killed one of its commanders in an aerial raid in Gaza.
Israel dropped leaflets over Gaza on Thursday, warning many of its 1.5 million residents to avoid areas within 300 metres (yards) of the border fence with Israel.
The mortar bombs and the rocket fired at Israel earlier on Thursday caused no casualties, an Israeli military spokesman said. The number of such attacks has risen in the past few weeks after months of relative calm since the Gaza war. (Writing by Allyn Fisher-Ilan; editing by David Stamp)