CAIRO -- At least 10 Egyptian women and children died Tuesday when a small bus carrying about two dozen people slid off a ferry and plunged into the Nile River just outside Cairo, health authorities said.

The cause of the accident was not immediately clear. Nine other passengers were injured in the accident in Monshat el-Kanater town in Giza province, the Health Ministry said in a statement. Giza is one of three provinces forming Greater Cairo.

At least five women were missing, according to state-owned media. Giza provincial Gov. Ahmed Rashed said the bus was retrieved from the river and rescue-and-search efforts continued.

Six of the injured were treated at the site while three others were transferred to hospitals. The ministry didn’t elaborate on their injuries.

An earlier list of the dead obtained by The Associated Press showed six were minors.

According to the state-owned Akhbar daily, about two dozen passengers, mostly women, had been in the bus heading to work. It said security forces detained the driver.

Ferry, railway and road accidents are common in Egypt, mainly because of poor maintenance and lack of regulations. In February, a ferry carrying day laborers sank in the Nile in Giza, killing at least 10 of the 15 people on board.