Officials said the preventive security chief in Gaza, Rashid Abu Shbak and the head of Palestinian general intelligence, Amin Hindi, submitted their resignations to Palestinian President Yasir Arafat "because of the state of chaos."
Their resignations came after a second senior Palestinian security official and four French nationals were abducted on Friday - hours after another senior security official was briefly kidnapped.
Palestinian officials later said all of the French hostages had been set free.
Colonel Khalid Abu Alula, Director of Military Coordination in southern Gaza, was taken from his car as he returned to Gaza City from the town of Khan Yunis
However he was released on Saturday morning.
"I was freed this morning and was well treated," the colonel said.
Palestinian security officials said the kidnappers were Palestinian policemen who had recently been fired from their jobs. The officials said that earlier in the day Alula had refused their request to help reinstate them.
Palestinian security officials also said five French citizens were kidnapped by armed Palestinian men as they drank coffee in Khan Yunis on Friday.
The motive behind their capture was not clear.
Calls for accountability
Just hours earlier, Palestinian armed men briefly kidnapped the chief of police for the occupied Gaza Strip and West Bank, Ghazi al-Jabali, and released him only after Palestinian President Yasir Arafat agreed to meet their anti-corruption demands.
The Jenin Martyrs' Brigade, part of Arafat's Fatah faction, claimed responsibility for al-Jabali's kidnapping, in one of the boldest challenges to Arafat's authority by Palestinians seeking security and governmental reforms.
Abu Iyad, a spokesman for the Brigade, told Aljazeera al-Jabali was kidnapped "to hold him accountable for his mistakes against our people."
Iyad alleged al-Jabali was corrupt and accused him of "making and accepting bribes, thereby undermining the progress of the Palestinian people".
"We gave three years to the Palestinian Authority to carry
out reforms. We waited a long time. But they didn't do anything. We are doing this in our way," said Abu Iyad.
Arafat agreed to the kidnappers' demands to dismiss al-Jabali and put him on trial for suspected corruption which led to the police chief's immediate release, added Iyad.