At least six people have been injured and more than a dozen properties destroyed after African Union forces opened fire on demonstrators in the Somali coastal town of Marka, witnesses and officials have told Al Jazeera.
"It is the second day we are been attacked by them. We are protesting because we do not want them in our town," a trader, who only gave his first name as Abdi Fatah as he feared for his safety, told Al Jazeera on Monday.
"They are supporting warlords with blood on their hands. They destroyed more than 12 buildings."
The confrontation started on Sunday when an AMISOM (African Union Mission in Somalia) water tanker was targeted by an IED allegedly laid by the armed group al-Shabab.
Locals said AMISOM responded by opening fire and arresting locals youths, triggering protests by people in the town.
"I was forced out of my home. Are they here to fight civilians or al-Shabab? I do not know what I did to them," a mother, who did not want to be named for security reasons, told Al Jazeera.
Government officials denied the residents' claims, saying al-Shabab infiltrators were responsible for the troubles.
"They were not protesters. They were youths sent by al-Shabab. They were carrying the al-Shabab flag," Abdul Khadir Sheikh Mohamed Noor, Lower Shabelle governor, told Al Jazeera.
Noor confirmed the number of injuries but said: "No one destroyed any properties. They were old buildings in the old part of the town."
Colonel Ali Houmed, an AMISOM spokesman, denied his forces had opened fire on the demonstrators or made arrests.
"As is standard operating procedure, AMISOM forces maintained their defensive postures, secured the area and did not open fire," Ali said.
"AMISOM does not have a mandate to arrest civilians and we did not arrest civilians.
"Our work in Somalia is to support the efforts of the Somali national security forces and mentor a capable and professional force that will take charge of this country's security affairs."
Lower Shabelle, the breadbasket of the horn of Africa country, has in recent months witnessed deadly clan clashes with more than one 100 people killed this year alone.
Al-Shabab were pushed out of the strategic port town two years ago but still carry out bombings and assassinations in Marka.
Follow Hamza Mohamed on Twitter: @Hamza_Africa