The BBC has not been able to verify the reports.
Goma, a major city of more than a million people, was captured after the Rwanda-backed M23 executed a rapid advance through eastern DR Congo.
The city was plunged into chaos, with bodies lying in the streets and missiles reportedly flying over residential homes.
Footage from last week’s jailbreak showed people fleeing from the building as smoke rose in the background. Heavy gunfire could also be heard.
In a separate video, people believed to be the escaped prisoners, filed through Goma’s streets.
More than 2,000 people were killed as the M23 clashed with the Congolese forces and their allies, DR Congo’s government has said.
The UN says at least 900 people were killed and almost 3,000 injured. It was unclear why the UN and DR Congo’s death tolls vary.
Earlier this week, the rebels announced a ceasefire on humanitarian grounds.
However, the M23 launched a new offensive on Wednesday, reportedly capturing the town of Nyabibwe.
Nyabibwe is about 100 km (60 miles) from Bukavu – the east’s second-largest city, and the reported target of the rebels’ most recent advance.
The Congolese authorities have enlisted hundreds of civilian volunteers to help defend Bukavu.
Back in Goma, where residents are adapting to life under the M23, there are fears of a cholera outbreak.
Stephan Goetghbuer, a regional lead from the charity Medicine Sans Frontieres, said: “Access to water has been cut for days, corpses have been lying in the streets and waterborne diseases such as cholera are a real threat.
“Some of our cholera treatment centres are full and have been expanded.”
