Five people were killed and 10 wounded in an attack by Palestinian militants near an army base in the central Gaza Strip tonight.
Israel Radio said initially that two suicide bombers had staged the attack but later said a huge bomb was detonated outside the Karni crossing between Israel and Gaza, and it was unclear whether suicide bombers were involved.
Rescue services said gunmen were firing mortar rounds at the site shortly after the explosion and that Israeli troops exchanged fire with militants.
Israeli medics said they were treating five wounded but had difficulty reaching other casualties due to gunfire. The Israeli army had no immediate comment.
The attack came amid an upsurge in violence between Israelis and militants defying calls by newly elected Palestinian President Mahmoud Abbas, a moderate, to stop the violence of a four-year-old uprising.
Three Palestinian militant groups claimed joint responsibility for the attack, including Al-Aqsa Martyrs Brigades - a faction of Abbas's Fatah movement - Hamas and the Palestinian Resistance Front.