Army holding M23 fighters, including top comander, official says.
Group will seek to resolve grievances through "political means only."
Uganda protests as shells landing within its borders injure five.
More expected to flee as fighting intensifies near border.
The Congolese army colonel marched triumphantly into town, welcomed by cheering crowds waving palm leaves after his soldiers retook this base in their latest offensive to quash the M23 rebels.
The fifth rebel-held town to be seized by the Congolese army recently.
Congo's M23 rebels clashed with government troops on near the eastern city of Goma.
M23 allegedly bankrolling rebellion by selling gold to exporters.
Accusations heighten tension along countries' shared border.
Follows a week of heavy fighting between U.N. troops and rebels.
