The protests were in response to the deaths of at least 55 people in a stampede at a religious festival of the Oromo people on Sunday.
The protesters burnt trucks and machinery at the Dangote Cement Factory in Ada Berga, the state-affiliated Fana Broadcasting Corporate reports.
A pro-opposition Amharic-language website, ZeHabesha.com, also covered the story saying protesters allegedly freed prisoners after setting ablaze a police station in the Bule Hora area.
A court and government-owned vehicles were also torched, it adds.
Activists say the security forces opened fire at the festival, causing the stampede.