There are reports of a total of four explosions, according to news agency AFP.

The bombs went off in the morning rush hour on three different stations.

NRK website reports that at least one person is injured by a homemade bomb at a station, while a private TV channel quoted sources as saying that three people have received minor injuries in an explosion at the station Shubra El-Kheyma.

The bombs should have been primitive and had little explosive force, according to a police source.