Five Palestinians and an Italian journalist were killed in Gaza Wednesday when Israeli ordnance detonated as experts tried to disable it just hours before the end of a 72-hour truce.

The blast occurred in the northern town of Beit Lahiya as Egyptian mediators scrambled to persuade Israeli and Palestinian negotiators to extend a three-day ceasefire, which expires at midnight (2100 GMT).

Negotiators in Cairo addressed the thorny issue of the Israeli Gaza blockade on Tuesday night, as the second day of a 72-hour truce neared its end.

As Gaza's residents ventured out to try to piece together their battered lives, Israeli and Palestinian negotiators held a second round of indirect talks aimed at finding a durable end to the five-week confrontation.

Human Rights Watch on Tuesday demanded that Egypt's President Abdel Fattah al-Sisi and two other officials be investigated for their roles in a brutal crackdown that killed hundreds in likely "crimes against humanity".

Security forces stormed two sit-ins of supporters of ousted President Mohamed Morsi in Cairo's Rabaa al-Adawiya and Nahda squares on August 14, 2013, resulting in what HRW termed "one of the largest killings of demonstrators in a single day in recent history".

An Israeli delegation arrived in Cairo on Monday for indirect negotiations with Palestinians on a durable truce in Gaza, Egypt and Israeli officials said.

The Palestinian delegation meanwhile was already locked in talks with Egyptian intelligence mediators, who will relay their demands to the Israeli negotiators, a Palestinian official said.

Egyptian troops have killed 11 militants in shoot-outs in the restive Sinai Peninsula where security forces have battled an insurgency since president Mohamed Morsi's overthrow, the army said on Monday.

An Israeli delegation arrived in Cairo on Wednesday to discuss with Egyptian officials a possible ceasefire in the Gaza Strip, airport officials said.

Cairo, a key mediator in truce negotiations between Israel and Gaza's Hamas rulers, was also expected to host a Palestinian delegation later this week.

Three people were killed when two bombs they were carrying in a pick-up truck went off prematurely south of Cairo, Egyptian government and security forces announced on Wednesday.

The three, who were allegedly planning an attack, were killed outright when the truck was completely blown apart in the village of Shurafa.

Egyptian troops have killed 14 jihadists in shoot-outs in the restive Sinai Peninsula, scene of an insurgency since the ouster of Islamist president Mohamed Morsi, the army said Sunday.

A son of ousted Egyptian president Mohamed Morsi, who was sentenced to a year in prison for possession and use of hashish, was arrested early Friday at a train station south of Cairo, security officials said.

Abdullah Morsi, 19, who security officials said was on the run, was arrested while boarding a train heading to Upper Egypt. His arrest was also reported by the official MENA news agency.

At least 17 people were killed in Egypt on Tuesday when a bus ploughed into a truck south of Cairo, state television reported.

The accident occurred near the town of Safaga, 570 kilometers (about 355 miles) south of Cairo, the report said, adding that 25 other passengers were injured in the crash.