Congolese security forces on Tuesday tried to slow the advance of Rwanda-backed M23 rebels who say they have captured Goma after entering eastern Congo's largest city, as U.N. officials reported violence,

M23's last occupation of Goma was short-lived, and within a year they were a defeated force. This time, things are different.

Rebels led by the M23 group claim to have taken control of Goma, a key city in the eastern Democratic Republic of the Congo.