Palestinian security forces arrested one Palestinian accused of violating a truce with Israel, the first such arrests under a U.S.-backed peace plan, prompting a protest by gunmen, who marched in the street and fired volleys into the air. Seven other Palestinians were arrested in Gaza City and the town of Khan Younis, apparently for firing anti-tank rockets at the Jewish settlement of Kfar Darom on Wednesday. The rocket fire injured four people. The Palestinian security chief, Mohammed Dahlan, had assured Israel he would go after anyone who breaks the cease-fire, including those who attacked Kfar Darom. Late Thursday, several dozen Palestinians, led by about a dozen gunmen shooting in the air, marched in Gaza City to protest the arrests. Marchers also set off homemade grenades, but there were no clashes with police. Touring northern Gaza on Thursday, after Israel's withdrawal four days earlier, Palestinian Prime Minister Mahmoud Abbas denounced the shelling. "This is an act of sabotage which we cannot accept," he said. However, Abbas has rejected an armed confrontation with Palestinian groups, fearing a civil war, preferring to negotiate an end to armed attacks. Abbas was to meet with officials from Islamic Jihad on Friday. Also Friday, another rocket fired from Gaza landed in an agricultural area of a small Jewish farming village, the army said. No one was injured. Israeli forces arrested 12 more Palestinians in overnight raids in the West Bank, the Palestinian sources said Friday. **PHOTO CAPTION*** Israeli Defense Minister Shaul Mofaz (R) talks with Palestinian minister for internal security Mohammed Dahlan in Jerusalem 1 July. (AFP/Pedro Ugarte)