CAIRO (AP) — At least six Egyptian women died Tuesday after a vehicle carrying about two dozen people slid off a ferry and plunged into the Nile River just outside Cairo, authorities said.

The accident, which happened in Monshat el-Kanater town in Giza province, also injured nine other passengers, the Health Ministry said in a statement. Giza is one of three provinces forming Greater Cairo.

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

Giza provincial Gov. Ahmed Rashed said the microbus was retrieved from the Nile, and rescue efforts were still underway as of midday Tuesday.

The cause of the accident was not immediately clear.

According to the state-owned Akhbar daily, about two dozen passengers, mostly women, were in the vehicle heading to work when the accident occurred.

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.