At least 15 people were killed on Monday night in a brawl between Cairo street vendors and a shopkeeper, including 13 in a fire, a security source told AFP.
The source said two people died of gunshot and stab wounds in an initial brawl in central Cairo, and 13 more were killed after the shop they took refuge in was set on fire.
The source said the fight started "over an old disagreement on vendor spaces."
Eyewitnesses told AFP that the fight began after a cosmetics store owner asked peddlers selling fireworks outside his shop to move away.
When they refused he attacked them, opening fire with a machine gun, they said, adding that the vendors then launched lit fireworks into his shop, setting it ablaze.
Security forces and firefighters moved into the area in the wake of the fight and put out the fire.
They discovered the 13 bodies of people killed in the blaze and arrested several people, the source added.
A firefighter at the scene said "most of those killed in the fire suffocated to death."
The cosmetics shop was almost completely destroyed in the fire, its inventory blackened and burned and the front door broken down by the rescue services.
There were no initial indications that the deadly melee was linked to the political turmoil that has engulfed Egypt since the July 3 ouster of the Islamist president in an army coup.