Two bombs exploded simultaneously on two buses in a southern Israeli city killing at least 16 people and wounding 80 in the first major Palestinian attack inside Israel in nearly six months, Aljazeera correspondents and agencies reported. Two bombers are also thought to have died in the attacks on Tuesday. Quoting Israeli radio and medical sources, Aljazeera.net correspondent Ahmad Fayyd said 80 people were wounded. Of these five were in a critical condition and 12 in serious but stable condition. The Palestinian group Hamas claimed responsibility for the attacks. **Reaction*** Reacting to the explosions, the Palestinian Authority condemned it and called for an immediate cessation of such attacks. The explosions occurred on the two buses on the main intersection near the municipality offices of Beer Sheba, the largest city in southern Israel. The city is 40km west of Gaza City. The dead and the wounded were in the two buses, Aljazeera TV correspondent Walid al-Umari said. Israel TV showed images of the two burnt-out buses, with flames shooting through the roof of one of the vehicles. At least two bodies, covered in white sheets, lay on the ground nearby. Minutes later, police reported a third explosion, but rescue workers said it was a false alarm. **Palestinian ambulance attacked*** Earlier on Tuesday, Israeli troops opened fire on an ambulance at a military checkpoint in the southern Gaza Strip wounding a doctor and his driver, medics and a human rights group said. Palestinian medics said the two had sustained moderate injuries when troops opened fire on their ambulance which had been waiting for over three hours at the Abu Ghuli checkpoint, just outside the southern town of Khan Yunis. A spokesman for Physicians for Human Rights (PHR) confirmed the information saying the ambulance had been travelling northwards from Khan Yunis when it was seized at the checkpoint and held there for three hours without any justification. "It took half an hour to evacuate the two men and when they arrived at hospital, the doctor had lost a lot of blood," PHR's Shabtai Guld said. "We condemn this incident and ask the army to conduct an immediate investigation and to bring to justice anyone who fires on an ambulance," Guld said, adding that the group would file an official complaint. **PHOTO CAPTION*** Rescue workers spray water on the wreckage of a bus in Beersheba southern Israel in this image taken from television Tuesday Aug 31, 2004. (AP)