GAZA CITY (Ma'an) -- Israeli warplanes raided south and central Gaza late Thursday, targeting sites belonging to Hamas, witnesses said.

“Four residents were injured, including two children, as a result of the Israeli air strike in an empty plot in An-Naser neighborhood in Gaza city and all were transferred to Ash-Shefa hospital,” Hamas spokesman Adham Abu Selmeiyah from the ministry of health said.

Two other residents were injured in an air strike in the south of Gaza and were transferred to the Al-Aqsa hospital, he added.

Air strikes targeted a projectile launch site in southern Gaza and two bases belonging to Hamas' Al-Qassam Brigades near Khan Younis and in Gaza City.

The attack on the site in Gaza City also caused material damage.

An Israeli army spokeswoman confirmed the strikes but did not elaborate.

Earlier, reports said six projectiles were fired from Gaza since Thursday, causing no injuries.

Five Palestinians were injured a day earlier in a raid on the tunnel area in Rafah.

The past three days of rocket fire and Israeli air strikes represent the first significant recurrence of violence in the area since April 2011, when Israeli air strikes killed nineteen Palestinians, reportedly in response to a missile fired from Gaza which hit an Israeli bus killing a teenager.

Israel has imposed a blockade on the Gaza Strip since Hamas took control of the enclave in 2007.