Medics said the victims were killed in a missile attack on Khan Yunus in southern Gaza early on Friday, but were unable as yet to name the dead.
The latest deaths come just hours after an unmanned Israeli drone killed four unnamed Palestinians in a similar missile attack on the same refugee camp.
An occupation forces spokesman said the drone had targeted a group of armed men who were resisting the deployment of more Israeli troops and armour into the camp.
He added that the raids were carried out in a bid to stop Palestinian mortar and rocket attacks on nearby illegal settlements and the troops protecting them.
All 21 Israeli settlements in Gaza are due to be cleared in 2005 along with four out of 120 in the West Bank.
"This operation, the third in three weeks, will continue as long as necessary," a military spokesman said.
"Our objective is to limit as much as possible, through a series of interventions, Palestinian rocket and mortar fire and destroy their infrastructure."
In an earlier incident, two people were hurt by flying debris when Israeli soldiers blew up a house in Khan Yunus after dark, witnesses said.
The latest raid - the third in as many weeks - began when about 20 Israeli armoured vehicles entered the refugee camp.
In the resulting gun battle, four people aged between 17 and 32 were killed. Resistance movement Hamas gave the names of its dead as Yahya Abu Bakr and Sami Abu Khudair.
The third death was of Ammar Azzam, a member of al-Aqsa Martyrs' Brigades. However, 17-year-old Muhammad Abu al-Said was not known to belong to any armed resistance movement.
Meanwhile, a 16-year-old identified as Raziq Mazla was also shot dead by Israeli soldiers further south in Rafah near the border with Egypt and another two Palestinians were also shot dead in the occupied West Bank city of Nablus.