Dar es Salaam, Jan. 29 -- GOMA, DRC — Congolese security forces on Tuesday tried to slow the advance of Rwanda-backed M23 rebels who say they have captured Goma after entering eastern Congos largest city, as U.N. officials reported violence, looting and bodies in the streets.

The officials said hospitals are overwhelmed in Goma, a regional trade and humanitarian hub that is now a refuge for hundreds of thousands fleeing gunfire and shelling in the major escalation of one of Africas longest conflicts.

The violence echoed far from Goma as protesters in the countrys capital attacked at least 10 embassies, including those of France and the U.S., which urged citizens to leave the city.

Congos Foreign Minister Thérèse Kayikwa...