A Palestinian child was killed and her elder brother injured on Tuesday evening in a blast at their house in Gaza, witnesses and medical sources said.

Witnesses said that an Israeli airplane fired a missile at Al- Haddad's family house at al-Zeitoun neighborhood in southeast Gaza City, but there has been no comment yet from Israel.

Adham Abu Selmia, an ambulance spokesman, said that two-year- old Hadeel was killed, and that her three-year-old brother was slightly injured in the explosion.

The blast happened as militant groups continued firing rockets against Israel, with the armed group of Hamas, the Islamic movement that controls Gaza, taking part in the shelling for the first time in more than a year.

The factions say the rocket-fire aims at retaliating the death of six Palestinians, most of whom were militants, in Israeli military strikes that started Monday.

Hamas has often refrained from participating in cross-border violence that has been taking place every now and then for more than a year. Islamic Jihad and smaller groups used to take part in the waves of violence, while Hamas focused on calming down the situation.

The firing of Grads by Hamas is likely to trigger a fiercer Israeli military response.