One person died and five others were injured in Uganda on Sunday, police said, as security personnel used teargas and live bullets to disperse a demonstration against the beating up of arrested lawmakers in response to the stoning of a presidential convoy.

Police spokesman Emilian Kayima said a policeman trying to quell the unrest in Mityana, a town about 50 kilometers (30 miles) west of the capital Kampala, had fired at a minibus.

"One policeman fired bullets into a moving taxi (minibus) with passengers, injuring six people. Unfortunately one of them died," Kayima told the NTV Uganda channel.

"We are looking for the policeman who committed this act, which is very irresponsible. He will be arrested and will be subjected to due process."

On Aug. 13, supporters of an independent candidate participating in a parliamentary by-election stoned a motorcade carrying the veteran president, Yoweri Museveni, as he was leaving the town of Arua after campaigning for a ruling party candidate.

Five members of parliament and dozens of other people were detained shortly afterward on suspicion of taking part in the assault.

Two of the MPs were badly beaten up during their arrest, according to politicians and relatives who have visited them.

One of them is Francis Zaake, whose constituency includes Mityana. Images of Zaake posted on social media showed him lying on a bed, eyes closed, with wounds on his palm, a swollen face and a cut ear. Politicians who have seen him in hospital in Kampala have said he is on life support.

On Thursday, four of the detained MPs and dozens of others were charged with treason and unlawful possession of firearms and ammunition for their alleged role in stoning the convoy.

Museveni has been in power since 1986. His critics say he is set to rule for life after parliament last year scrapped an age cap on presidential candidates.