GAZA CITY, Gaza Strip (AP) – A rocket-propelled grenade slammed into the home of Palestinian Arab Prime Minister Haniyeh on Tuesday in what his Hamas movement said was an assassination attempt by Fatah. Neither the leader nor his family were hurt in the attack.

Exasperated Egyptian mediators said the bitter rivals Hamas and Fatah turned down an appeal to meet for truce talks.

Before the attack on Haniyeh’s home, four mortar shells slammed into the Gaza City office of Palestinian President Abbas of Fatah, who was in the West Bank at that time. No one was hurt in the Abbas compound.

In all, 19 Palestinian Arabs were killed over two days in a new spike in the yearlong Hamas-Fatah power struggle. Some people were shot at close range in street executions, others in shootouts that turned hospitals into battle grounds. 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, which is turning more brutal with each day, 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, Lieutenant Colonel Burhan Hamad, said neither side has 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.

Colonel 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.

Both sides have become more and more ruthless in recent days. Two men were thrown off high-rises earlier in the week, several people have been shot at from close range in field executions, and hospitals have become firing zones.

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 the home of Haniyeh 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. Hamas spokesman Fawzi Barhoum accused Fatah of targeting Palestinian institutions to bring down Hamas. “They crossed all the red lines,” he said of Fatah.

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.

In fighting Monday, gunmen, apparently from Hamas, laid siege to the house of a senior Fatah official in northern Gaza, then dragged him outside and killed him, security officials said. Medics said he was hit with 45 bullets. Nabil Abu Rdeneh, an aide to Abbas, said no end was in sight. “You can see for yourself there’s no taste for a cease-fire right now,” he told The Associated Press by telephone, blaming Hamas.

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.

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.

Hamas brought Fatah into its government in March in an effort to quell the internal strife, but the fighting reignited in mid-May over an unresolved dispute over who controls the powerful security forces.