A small bomb exploded early Monday in a Cairo neighborhood near the Pyramids, shattering the glass of two parked cars but injuring no one, police said. But the Interior Ministry played the matter down, saying the blast was caused by fireworks. Investigators believe that someone threw the bomb from a balcony in the neighborhood of Giza, a few kilometers away from the landmark Pyramids, said a police official, who spoke on the condition of anonymity because he is not authorized to speak to the media. The target of the bomb, which was packed with nails, was not known, the official said. But the Interior Ministry later issued a statement saying the blast was caused by "some individuals playing with fireworks when one fell and hit a car, causing some damage." The statement did not mention a nail bomb or damage to another car. It was not immediately possible to reconcile the difference between the two versions. Egyptian authorities are generally cautious on security-related matters and wary about their impact on the country's lucrative tourism industry, one of the economy's mainstays.Winter is the high tourist season at the Pyramids, which are located on Cairo's western edge.