Hamas's violent dispersal of a mass Fatah rally in Gaza on Monday was a "heinous crime," Palestinian Authority President Mahmoud Abbas's office said. "This heinous crime is decisive evidence that the coup leadership of Hamas is out of step with the national values and customs and is using blind force and the most bloody and brutal techniques against our people in Gaza," said a statement by Abbas's office. Abbas is currently in Egypt. The incident was a sign of Hamas's growing difficulties, former Gaza strongman Mohammed Dahlan of Fatah said Monday. "The shooting and killing, these sad and shameful scenes carried out by the Hamas gangs against innocent people and civilians today, are a sign of the failure and breakdown of Hamas' path," Dahlan said. Hamas security forces on Monday opened fire at a mass rally commemorating the death of the late Palestinian leader Yasser Arafat, violently dispersing close to 250,000 people who had gathered in the largest public display of support for the rival Fatah movement since Hamas seized control of the Gaza Strip in June. Six civilians were killed and at least 85 people were wounded, hospitals and witnesses said. Among the critically wounded was a Hamas policeman who was shot in the head. Monday's rally was Fatah's largest public gathering since Hamas overran the Strip in June, expelling the security forces of Palestinian Authority President Mahmoud Abbas. Abbas has been using the third anniversary of Arafat's death to rally support on the Palestinian streets. Demostrators carrying pictures of Arafat, yellow Fatah flags and wearing trademark black and white Arab headdresses, gathered in a large court in downtown Gaza City. Hamas security officials said they fired toward protesters who threw stones at security compounds. Hamas police were positioned on rooftops around Gaza City, and protesters were seen running for cover at street corners. Smoke was rising around the edges of the rally court yard, but thousands of supporters still milled around, as firing was heard from around the rally. Eyewitnesses said Hamas gunmen roamed the streets later and started detaining protesters. Hamas said one of the dead was killed by Fatah gunmen who had fired from rooftops, but that could not be confirmed. A Fatah official said the person, a Fatah supporter, was shot on his way to the rally by a racing car, accusing Hamas of the shooting. The Fatah official spoke on condition of anonymity because he was not authorized to speak to the media. Hamas said five of its policemen were injured, one seriously, and accused Fatah gunmen.