( AP ) - Hamas fighters on Tuesday captured several positions from the rival Fatah movement and threatened to step up the offensive after a rocket-propelled grenade hit the home of the Hamas prime minister. Palestinian President Mahmoud Abbas accused his Hamas rivals of staging a coup.
There were no injuries in the early-morning attack on Prime Minister Ismail Haniyeh's home - the second in two days. But the attack underscored the increasingly ruthless nature of the fighting, which has killed 18 people in recent days. Exasperated Egyptian mediators said the bitter rivals turned down an appeal to meet for truce talks.
Heavy gun battles erupted in several locations, in what security officials described as a Hamas assault on positions of the Fatah-allied security forces.
Hamas-affiliated radio stations said the group took control of security installations in northern and central Gaza, as well as the southern town of Khan Younis.
Hamas also demanded that Fatah-allied security forces abandon their positions, threatening to attack those who remained in their posts.
"The warning which we have given you to surrender has ended, and we will attack this position of Zionist collaborators," Hamas warned over a mosque loudspeaker in Gaza City, shortly before taking up positions near the headquarters of the pro-Fatah Preventive Security Service. Later, there were heavy exchanges of fire.
In the West Bank, where Fatah forces are much stronger, Fatah gunmen threatened to retaliate by killing Hamas leaders. The deputy transportation minister of Hamas was seized by Fatah gunmen, Hamas said. There was no word on his condition.
Col. Nasser Khaldi, a Fatah commander in southern Gaza, confirmed his men were on the defensive. Khaldi said Abbas, the leader of Fatah, must give orders now to fight back.
"There is a weakness of our leaders," he said. "Hamas is just taking over our positions. There are no orders."
In the southern town of Khan Younis, streets were deserted. A member of the Fatah-allied forces there said that Hamas took several smaller Fatah positions, but that the main compound holding three branches was still under Fatah control. The officer said Hamas has taken over a building next to the compound. "Our orders are to defend ourselves if they come, but not to attack," he said.
Abbas was meeting with Fatah leaders at his headquarters in the West Bank to discuss the next steps. He accused Hamas of trying to seize control of Gaza by force and appealed for a new cease-fire. Earlier, four mortar shells hit his Gaza City compound, but caused no injuries.
"Some Hamas political and military leaders are planning to stage a coup, ... thinking they will be able to control Gaza by force," Abbas' office said in a statement.
Hamas and Fatah have been locked in a violent power struggle since Hamas defeated Fatah in January 2006 legislative elections, ending four decades of Fatah rule.
The sides agreed to share power in an uneasy coalition three months ago, but put off key disputes, including wrangling over control of the security forces. Most of the forces are dominated by Fatah loyalists, while Hamas has formed its own militia over the past year in addition to the thousands of gunmen at its command.
In all, 18 Palestinians have been killed in two days in the latest spike of violence, which has grown increasingly brutal. Some people were shot at close range in street executions, others in shootouts that turned hospitals into battle grounds, while others were thrown from rooftops. Residents huddled indoors, and university exams were canceled.
Each group used Web sites and text messages to call for the execution of the other side's military and political leaders. Both sides described the fighting as all-out civil war. In all, more than 80 people have been killed since mid-May, most of them militants.
The head of the Egyptian mediation team, Lt. Col. Burhan Hamad, said neither side responded to his call to hold truce talks Tuesday.
"It seems they don't want to come. We must make them ashamed of themselves. They have killed all hope. They have killed the future," said Hamad, who brokered several previous short-lived cease-fires.
Hamad said both sides were about equal in firepower. "Neither can have a decisive victory," he said. "To be decisive, they need weapons that neither side has."
He said he would call civilians out into the streets to protest if the two rivals did not agree to stand down.
Islam Shahwan, a spokesman for the Hamas militia, brushed aside the latest truce efforts. "It's all talk. It's not serious," he said.
On Tuesday morning, a gun battle erupted at the European Hospital in the southern Gaza town of Khan Younis. Hamas gunmen controlling the rooftop traded fire with Fatah-allied security forces posted nearby. Fifteen children attending a kindergarten in the line of fire were rushed into the main building of the hospital, funded largely by European donations.
Earlier in the day, a rocket-propelled grenade hit Haniyeh's home in the Shati refugee camp on the outskirts of Gaza City. His son, Abdel Salam, said a grenade hit the side of the house, damaging it, while the family was inside.
A Hamas Web site described the incident as an assassination attempt by Fatah. "They crossed all the red lines," said Hamas spokesman Fawzi Barhoum.
Elsewhere, a member of the Hamas military wing was kidnapped and executed by Fatah gunmen. The dead man was identified as a cousin of Abdel Aziz Rantisi, a Hamas leader Israel assassinated in 2004.
Separately, Hamas gunmen attacked the home of a senior Fatah security official with mortars and grenades, killing his 14-year-old son and three women in the house, security officials said. Other Fatah gunmen stormed the house of a Hamas lawmaker and burned it to the ground.
The fighting also spilled into the West Bank, with Palestinian security forces seizing two employees of the Hamas-linked Al Aqsa TV station in the city of Ramallah and confiscating equipment. Fatah gunmen said Hamas leaders in the West Bank, a Fatah stronghold, would be targeted if Hamas doesn't halt its attacks in Gaza.
The latest fighting disrupted final exams for university and high school students. The three Gaza universities called off final exams set for Tuesday. High schools were trying to move test centers to areas out of the range of fire, said Mohammed Abu Shkeir, the deputy minister of education