GAZA CITY (CNN) -- Israeli aircraft fired a rocket Friday targeting a car carrying Islamic Jihad militants, killing one person and wounding another, Palestinian sources said.The sources said the militants were attempting to fire rockets toward Israeli sites in Beit Hanoun, just northeast of Gaza City. The Israel Defense Forces confirmed that the military targeted militants, saying they were on their way to carrying out a rocket attack.Earlier, the Israeli military said militants fired two rockets from Gaza -- one fell inside Gaza and the other landed in an open field in Israel.The military said it has launched at least three missile strikes on an open field it says Palestinian militants use to fire rockets. There were no reports of damage or injuries.Late Thursday, an Israeli airstrike hit a car carrying Palestinian militants north of Gaza City, killing seven people, including an Islamic Jihad commander and three other members of the group, Palestinian and Israeli security sources said. Three civilians, including a 15-year-old boy and a 60-year-old man, also were killed and at least 14 other Palestinians were wounded, some of them seriously, a source said.The strike came just hours after Israeli Prime Minister Ariel Sharon vowed to crack down on terrorists in response to a suicide bombing on Wednesday that killed five Israelis and wounded 28 people in a market in Hadera, in central Israel.Sharon also said he would not meet with President Mahmoud Abbas until the Palestinian leader takes "serious and tangible action against terrorism."Islamic Jihad claimed responsibility for Wednesday's suicide bombing.Sharon approved a number of measures, including targeted killings and arrests, to prevent terror attacks, a Sharon adviser said. (Watch the aftermath of the deadly bombing -- 3:25)Israeli forces surrounded the home of the alleged Hadera bomber, Palestinian sources said, and they also entered the Palestinian refugee camp of Nur al-Shams in the West Bank. No other details were available.On Thursday afternoon, Israeli troops entered Jenin and arrested Abdel Halim Izzedine, a spokesman for the Islamic Jihad, according to Palestinian security sources. The Israeli forces, traveling in jeeps and helicopters, immediately began a withdrawal from Jenin after the arrest, the sources said. Israeli military sources confirmed that the army had been operating in Jenin, carrying out arrests. The sources said the troops had withdrawn from the West Bank town. Islamic Jihad claimed responsibility for Wednesday's bombing in a crowded Hadera marketplace. In a telephone call to CNN, the group said the attack was in retaliation for Monday's killing of one of its leaders in the West Bank.Fat'halla Sa'adi, 26, the head of Islamic Jihad in Tulkarem, was killed by Israel forces along with another member of the group, the Israeli military said.Sa'adi was planning more attacks, including "a suicide bombing inside Israel ... to be committed within the next few days," according to a statement Monday from the Israeli Defense Forces.The Hadera attack was the first inside Israel since an August 28 suicide bombing in the southern town of Beersheba that wounded 21 people.Palestinian negotiator condemns attackChief Palestinian negotiator Saeb Erakat said the Palestinian Authority condemned the attack. He urged all sides to maintain the cease-fire agreement reached by Israel and the Palestinian Authority in February."We don't want to go back to this vicious cycle," Erakat said. "We've been there before. Israelis and Palestinians will pay the heaviest price if the cessation of violence is undermined."Ra'anan Gissin, spokesman for Sharon, dismissed the Palestinian Authority's condemnation and accused its leaders, including Abbas, of "sitting back and doing nothing."Hadera was the site of numerous terror attacks targeting Israeli civilians in 2001 and 2002. The most recent previous attack in Hadera was in October 2002, when a suicide bomber detonated an explosives-laden vehicle near a bus packed with passengers. Fourteen people were killed.U.S. urges Palestinian Authority to actIn Washington, White House spokesman Scott McClellan condemned the Hadera terror bombing as a "heinous attack on innocent civilians" and called on the Palestinian Authority "to do more to end the violence."On Thursday, Israeli airstrikes also targeted a road in Gaza City and a bridge in Beit Hanoun, also in Gaza, the IDF said. For a second day, the IDF said, Israeli airstrikes were aimed at fields in Gaza. There were no reports of injuries in those strikes. The actions came after a Qassam rocket was fired from Gaza into Israel.Earlier this week, the IDF closed off the West Bank because of security alerts. Two crossings into and from Gaza were closed after the Hadera bombing.CNN's Michal Zippori contributed to this report.