Israeli helicopters fired missiles at a car in Gaza City early Thursday, killing at least two people, residents said. It was the second Israeli air strike in Gaza City in six hours. Two Hamas members and five bystanders were killed in the first attack. The latest attack came just after midnight. The bodies of the dead were taken to Shifa Hospital in Gaza City, It was not immediately known who they were. Also, one person was seriously wounded, doctors said. The Israeli military had no comment. Residents said ambulances raced to the scene in the Zeitoun neighborhood in Gaza City. They said they heard four explosions and saw Israeli attack helicopters flying away from the scene. **Jerusalem Bus Blast Kills 16, At least 6 Palestinians Died in Gaza by Israeli Missiles*** A Palestinian bomber blew himself up on a bus in downtown Jerusalem on Wednesday, killing at least 16 people and wounding about 60, Israeli witnesses said said. The bombing followed a threat by the Islamic group Hamas to take bloody revenge for Tuesday's botched missile attack by Israel on one of its leaders, Abdel Aziz Rantisi, who was wounded. There was no immediate claim of responsibility. Immediately after bomb blast, Israeli helicopters start with new missile attack on Gaza Strip, killing at least six Palestinians and wounding 25 Abu Dhabi TV reported. The explosion went off during afternoon rush hour on city bus No. 14 on Jaffa Street, Jerusalem's main thoroughfare, near Mahane Yehuda, Jerusalem's outdoor market which repeatedly has been targeted by Palestinian in the past. Paramedics and police reported that 15 people were in serious condition. The blast blew out windows and tore a large hole into the left side of the red-and-white bus. The bus had just left Jerusalem's nearby central bus station when the explosion occurred. Ofir Alon, a witness, said he was standing on a nearby street corner at the time. "I heard a blast ... Then I heard people yelling and running in the direction of the explosion, screaming `attack,'" he said. Earlier Wednesday, Israeli Prime Minister Ariel Sharon was unapologetic about the strike against Rantisi, despite President Bush's reprimand that the attack made it harder for the Palestinian prime minister to fight terrorism. Tuesday's attack jeopardized the so-called "road map," a U.S.-backed plan for peace and Palestinian statehood by 2005. Bush has invested his presidential prestige in the initiative, formally launching it with Sharon and Palestinian Prime Minister Mahmoud Abbas at a summit last week in the Jordanian resort of Aqaba. "We will make no concessions to terror," Sharon told his Cabinet on Wednesday, according to a government official. "We made this clear to all the White House officials and to the Palestinians before the Aqaba summit." Abbas denounced the missile strike as terrorism, appealed to the United States to intervene, and said he would keep trying to reach an understanding with Hamas and other militias. Abbas opposes a crackdown on the armed group, saying there is no substitute for dialogue and that he will not risk a civil war. Abbas has been unequivocal in his condemnation of violence against Israel, while Arafat has been more ambiguous and stands accused by Israel and the United States of involvement in terrorism. Sharon on Wednesday was quoted as saying he would not wait for Abbas to reach an agreement with Hamas. "If the Palestinian Authority does not perform its duties, we will do so instead," Sharon told the Yediot Ahronot daily. The strike against Al-Rantisi was widely criticized in Israel, including by politicians who generally support targeted killings. Israel has carried out dozens of such attacks in the past 32 months in its campaign to prevent bombings and shootings. **PHOTO CAPTION*** The blast came during rush hour (Al-Jazeera TV)