The Egyptian police's crime lab report says the bomb that killed a French teenager and injured 24 others at a famous Cairo bazaar was a crude device consisting of gun powder detonated by a washing machine timer.
The bombed weighed half kilogram and was filled with gunpowder, rocks and pieces of metal, according to the report which appeared in newspapers Tuesday.
The report said no nails were found in the bomb, contributing to the limited casualties.
The bomb was placed inside a plastic jar under a stone bench next to the revered Hussein mosque and the Khan el-Khalili bazaar, a poular tourist destination.
The blast Sunday night was the first attack targeting foreigners in Egypt in three years.