A ferryboat sunk in the Nile river in Cairo's twin city Giza on Wednesday leaving 15 passengers dead, while six injured passengers were rescued, the Interior Ministry said.
"A barge collided" with the ferryboat, "shattering" the latter, the ministry cited a security source as saying in a statement issued on its Facebook page.
The captain of the barge, "who caused the accident" and his assistant were arrested, the security source added.
A Giza health official said a state of emergency has been declared in hospitals in Giza, in case the number of casualties is high.
In March, a private company bus carrying workers fell off the ring road and into a canal branching from the Nile river, leaving a dozen dead.