The deadly air raid came as merchants in the Gaza Strip closed their shops in a half-day strike to protest against Israel's blockade of the Hamas-ruled territory.
Saturday's strike, called by the Popular Committee Against the Siege (PCAS), a politically independent group headed by Jamal al-Khudari, a Palestinian parliamentarian, was to be part of a day of events and demonstrations.
In Gaza City, hundreds of people marched to the Unesco office to submit a letter to Ban Ki-Moon, the UN secretary-general, asking for his help.
They waved banners showing items that are now in short supply because of the blockade.
"Our message is clear, and it is to break the siege imposed on the Gaza Strip and to motivate the Arab and Islamic and international community on the official and popular level," al-Khudari said.
Refugee camp raid
Earlier on Saturday, Israeli military forces raided the Al-Ein refugee camp, west of the city of Nablus, in the West Bank.
They arrested Majdi Mabroukah, the leader of the military wing of the Popular Front for the Liberation of Palestine (PFLP).
Mabroukah had been on Israel's "wanted" list for three years.
Also on Saturday, Hamas officials met Egyptian security officials for the third time in less than two weeks, a security source said.
"They are holding discussions in the town of El-Arish in north Sinai with Egyptian officials and then will head back to Gaza," the source said.
The Hamas delegation, led by Mahmud al-Zahar, a former foreign minister, entered via the Rafah crossing which was blown up by fighters on January 23, temporarily allowing Palestinians to flood into Egypt to stock up on food and supplies.
The border - Gaza's only gate to the world that bypasses Israel - was resealed on February 3 by Egyptian forces and Hamas.