GAZA CITY, Gaza Strip — Defying calls by Palestinian leader Mahmoud Abbas to halt armed attacks, assailants detonated a truck bomb and opened fire at a border crossing between the Gaza Strip and Israel yesterday, killing six Israelis and wounding five others before they were killed.

The assault came hours after spokesmen for Hamas and Islamic Jihad said in separate interviews that the anti-Israeli groups were prepared to discuss a possible cease-fire with the Israelis.

Abbas, who was elected president of the Palestinian Authority on Sunday, said yesterday that the Palestinians were ready to carry out their security commitments under the internationally backed "road map" peace plan. But he has been challenged by anti-Israeli groups that have kept up assaults in the Gaza Strip in an effort to portray a planned withdrawal as a retreat under fire.

Al Aqsa Martyrs' Brigades, an offshoot of Abbas' Fatah faction, Hamas and another group, the Popular Resistance Committees, claimed responsibility for the attack at the Karni border crossing, where goods are shipped to and from the Gaza Strip.

Sami Abu al-Zuhri, a Hamas spokesman, said that a meeting with Abbas was expected next week and that Hamas would consider a cease-fire under certain conditions.

"If the Israeli aggression against the Palestinian people stops and it is clear that the enemy wants quiet, then we will study it," Abu al-Zuhri said.