The latest attack, the day's fifth, was aimed at an unknown target. The fourth - minutes earlier - struck a car in Nusayrat refugee camp.
The vehicle took a direct hit from what witnesses said was a missile fired by an Apache helicopter, killing its two occupants.
Another missile was fired into a crowd of people gathered round the destroyed vehicle, causing at least 70 more casualties including at least six fatalities, according to Aljazeera quoting Palestinian medical sources.
Residents said one of the dead was a doctor who was treating victims when the second missile struck. The identity of the other victims was not immediately known, and the military did not comment.
Hundreds of camp residents charred carried pieces of the vehicle aloft and chanted, "Revenge, revenge."
Israel's Channel 10 TV said that none of the dead were "militants", characterising the refugee camp strike as a "mistake."
Also Monday night, Israeli helicopters fired missiles at a building in the Shujaiyya neighbourhood of Gaza City, the same structure that was hit in an earlier air strike on Monday, residents said.
Eleven people were wounded, they said. Israeli military sources said the attack was meant to finish the work of the first one.
Tonight's attacks followed a wave of airstrikes Monday by helicopters against targets in the densely populated areas of the Gaza Strip.
The first attack was aimed at Abd Allah al-Shami, a senior Islamic Jihad official who narrowly escaped being hit.
The rocket missed its target and exploded near a building opposite al-Shami's house, causing widespread damage.
Two members of Hamas armed resistance group were killed in the second airstrike on a car in the central Gaza Strip.
Aljazeera's correspondent said the two slain fighters from the military wing of Hamas, the Ezz al-Din al-Qassam Brigades, had been named as Khalid al-Masri, 28, and Iyad al-Hilo, 26.
“Marwan al-Khatib, a 35 year old Palestinian citizen, was also killed in the airstrike, as he was in his car near the targeted one,” she said.
“Eight Palestinians, including children, were injured, as the street was crowded with schoolchildren who were on their way home,” she added.
''The US backed Israeli assassination attempts and attacks against the people of Palestine will never stop the Palestinian resistance''
Abu Imad Al-Rifai,
The third strike hit a small shed in a field northeast of Gaza City causing no injuries, Palestinian security sources and witnesses said.
Al-Shami said: "Israel targets all people of Palestine including old, women and children every day.
"Israel has launched a violent war against Rafah and Jenin cities, targeting Palestinian people, killing their children and destroying their houses."
He added that the building which was destroyed next to his home was not a weapons factory.
"The owners of the house, a Palestinian family, were happily waiting for it to be built but Israel has deprived them of this happiness as their home has been completely destroyed."
Last year al-Shami, the founder of Islamic Jihad, said he was hopeful that he would not be targeted for assassination by Israel on the grounds he was a political and not a military leader.
Abu Imad Rifai, a representative of the Islamic Jihad Movement in Beirut told Aljazeera that al-Shami was safe and well.
Rifai added, ''The US backed Israeli assassination attempts and attacks against the people of Palestine will never stop the Palestinian resistance.''
A witness in Gaza City described the scene minutes before the attack.
''We heard the jet overhead and then heard a huge explosion, smoke was everywhere. I saw an ambulance arrive shortly after, at least five people were being carried away injured''.
The assassination attempt on Abd Allah al-Shami came only hours after three Israeli soldiers were killed in the West Bank on Sunday night. Al-Aqsa Martyrs' Brigade claimed responsibility for the killings.
The attempted assassination of al-Shami was the latest in a series of Israeli attacks on the homes of resistance leaders in Gaza.
The Israeli army denies targeting al-Shami saying that the rocket hit a weapons factory used by Hamas.