Fighting between Israeli troops and Hamas militants was briefly suspended in several flashpoint areas of Gaza on Wednesday to allow convoys of ambulances to retrieve the wounded, an ICRC spokeswoman said.
"A convoy of seven ambulances and two Red Cross cars went inside Shejaiya to evacuate the wounded," ICRC spokeswoman Cecilia Goin told AFP, saying the move had been coordinated with both Israel and Hamas.
A second convoy of nine ambulances and two Red Cross vehicles went into Khuzaa near the southern city of Khan Yunis, an area which also came under very heavy Israeli fire overnight, she said.
A third team went into the northern town of Beit Hanun, the agency said.
"We have coordinated with both Hamas and the Israelis to be able to take out the wounded," Goin told AFP, indicating both sides had agreed to hold their fire, although it was not immediately clear for how long.
There was no immediate comment from the Israelis and an AFP correspondent in Khuzaa said the shooting appeared to be ongoing.
Since the early morning, there have been major clashes between Israeli troops and Palestinian militants in Khuzaa, which lies on the Israeli border, some six kilometres (four miles) southeast of Khan Yunis.
Of the 27 Palestinians killed in fighting on Wednesday, most of the victims were in Khuzaa, medics say, although no exact number was quoted.
A similar bombardment began early Sunday in Shejaiya, a densely-populated district between Gaza City and the border, which medics say killed at least 75 people, with an AFP correspondent reporting scenes of mass destruction and bodies lying on the ground.