Egyptian army troops fought a four-hour gun battle with protesters in southern Cairo, in a dispute over land on an island of the Nile, security officials said. Three protesters were killed.
The officials said the disputed land on Qursayah island was owned by the armed forces but illegally seized during the chaos that followed last year's ousting of authoritarian president Hosni Mubarak.
The clashes broke out on Sunday when troops retook control of the plot. The officials say three civilians were killed and seven others wounded when fighting broke out on a road on the mainland across from the island.
Troops arrested 15 protesters who had used metal barricades and burning tyres to block an access road, the officials said. Five soldiers were wounded by gunfire in the clashes, about 1.5km from central Cairo.
A statement published by Egypt's official Mena news agency quoted a military spokesman as saying the land was first seized after the fall of Mubarak but soon retaken by the army.
About 60 civilians, mostly women, again took control of the land on Friday but were evicted early on Sunday after efforts for a negotiated settlement failed. The spokesman said the protesters opened fire first, and said 25 were arrested.
The island battle was the first involving the army since President Mohammed Mursi took office in June.