Palestinian gunmen dressed in police uniforms broke into a prison in the West Bank city of Jericho today and shot dead six Palestinian inmates, security sources said.
Four of the dead had been accused of killing two officials within President Mahmoud Abbas's Fatah faction in the West Bank city of Nablus last year.
The four were in prison awaiting trial. The other two victims were cell mates. Tawifiq Tirawi, the deputy head of intelligence in the West Bank and Gaza, said Palestinian authorities believed the attack was carried out by relatives of the two dead Fatah officials from a village near Nablus.
"Those who committed this crime will be brought to justice," Tirawi told reporters in Jericho, where a state of emergency was declared. The attack occurred at a Jericho prison run by Mr Abbas's intelligence service.
Meanwhile Israel killed three Palestinians in the Gaza Strip as it launched a series of air strikes on militant targets that wounded four other people.
The fighting overnight was concentrated in the southern Gaza town of Rafah, close to where Palestinian gunmen on June 25th seized an Israeli soldier, Corporal Gilad Shalit, in a cross-border raid.
The raid and Palestinian rocket fire triggered a massive Israeli ground and air offensive which over the past five weeks has killed at least 163 Palestinians, more than half of them civilians.
Medics and witnesses said two Palestinians were killed and another was wounded when a tank shell landed near a house in Rafah shortly after daybreak today.
An army spokeswoman said Israel had launched an air strike against two gunmen in the area.
A Hamas militant was also killed in an Israeli air strike, medics said.
A three-day old baby also died today after being dropped by her mother while fleeing advancing Israeli troops in her village near Rafah yesterday.
Israeli ground forces swept into the Rafah area yesterday to destroy what the army called "terrorist infrastructure".
Troops backed by armoured vehicles have since taken over a large area, carried out house-to-house searches and destroyed greenhouses and chicken farms. At least eleven people have been killed in the incursion since yesterday.
Israel has rejected demands by the armed wing of Hamas and the other groups to exchange Cpl Shalit for Palestinian prisoners.