A Palestinian toddler was killed Tuesday evening in an explosion south of Gaza City, medics said.

Emergency services spokesman Adham Abu Salmiya said in a statement that Hadil al-Haddad, 2, was killed and her brother was injured in the Zaitoun neighborhood of Gaza City.

A Hamas medical official told Reuters the cause of the child's death was not clear. Witnesses said she was killed when militants launched a rocket close by.

An Israeli military spokesman told Ma'an the army had not attacked that area. He said the army's initial investigation suggested al-Haddad's death was caused by a failed rocket launch by Palestinian militants.

Israeli airstrikes killed four men in northern Gaza on Monday and two teenagers were killed by Israeli shelling on Tuesday morning. Israel's army said the attacks were in response to rocket fire from the Gaza Strip.

An Israeli army spokesman told Ma'an that 25 rockets were fired into southern Israel on Tuesday.

The military wings of the Popular Front for the Liberation of Palestine and the Popular Resistance Committees said they had fired projectiles across the border on Tuesday in response to the barrage of Israeli attacks.

"If the enemy does not stop its crimes, the resistance will respond with all available defense means," the PRC's Nasser Salah ad-Din Brigades said in a statement.

Hamas' armed wing, the Al-Qassam Brigades, also fired rockets into Israel on Tuesday for the first time in over a year. For months, Hamas has stayed on the sidelines and discouraged smaller militant groups from firing rockets into Israel.

Fawzi Barhoum, a Hamas spokesman, said Israel's attacks prompted the group's military wing "to take a firm stance" and launch rockets.

Although Hamas usually holds its fire under an unofficial truce, Israel says it holds the ruling party responsible for any attacks from the Gaza Strip.

Ground operation

Israeli cabinet minister Silvan Shalom on Tuesday raised the prospect of a ground operation in Gaza.

"The more things deteriorate, the closer we come to a decision we don't want to make," Shalom told Israel Radio. "The prospect of a ground operation shouldn't frighten us."

"If this situation escalates, and I hope it won't, then all options are open. They know it. We know it. The international community knows it," Shalom added.

On Monday militants who crossed into Israel from Egypt's Sinai desert fired on Israelis building a barrier on that frontier, killing one worker. Soldiers shot dead two of the infiltrators.

In a video recording obtained by Reuters in Gaza, a group of masked men claimed responsibility for the Sinai incident on behalf of what they said was a newly formed Islamic movement, the "Shura Council of Mujahideen in the Holy Land".

The masked men used Islamic slogans, pledging to liberate the Holy Land from what they termed Jewish control.

A second video showed two men, one of whom said they were about to embark on a mission to attack "the Zionist forces on the border of Egypt and occupied Palestine", an apparent reference to Monday's incident on the Sinai border.

The first man said he was an Egyptian named Abu Salah al-Masri. The other said he came from Saudi Arabia and gave his name as Abu Huthiyfa al-Rathali. The videos could not immediately be verified.