Uganda's army has made a rare apology after soldiers were caught on film beating up a journalist who was covering a demonstration supporting detained MP Bobi Wine on Monday.
Other journalists were also beaten as they were reporting on the protests.
An army statement described the soldiers' conduct as "unprofessional" and said they would be arrested.
There has been political tension in Uganda after Wine, and four opposition MPs, were arrested last week.
Wine, who was a well-known musician before being elected an independent MP last year, is leading possibly the first major popular movement against President Yoweri Museveni by young people, says the BBC's Catherine Byaruhanga.
Most Ugandans alive today were not yet born when Mr Museveni came to power in 1986.
Earlier, New York-based Human Rights Watch called on the Ugandan police and military to stop attacks on the media and respect the rights of all protesters.
In footage shared online, Reuters photojournalist James Akena can be seen being beaten with a stick by two soldiers on a street in the capital, Kampala.
The beating carried on even after Mr Akena put his hands up and fell to his knees.
"The behaviour of the police or the security personnel has never been this way, so it is difficult to tell why this time round they have taken this new trend," Mr Akena told BBC Focus on Africa radio.
On Monday one person was killed and more than 100 arrested.
Last week, two journalists were arrested as they reported live from the northern town of Arua, where Wine's driver was killed during a bitterly contested by-election, which was won by one of the MP's allies, Kassiano Wadri.
Human Rights Watch says the beating and arresting of journalists is evidence the Ugandan authorities want to cover up the conduct of the security forces.
Wine, whose real name is Robert Kyagulanyi, remains in detention and is due to appear before a military court on Thursday on charges of unlawfully possessing firearms.
His family allege he has been severely assaulted in custody, but the military, which is holding the MP, denies this.
President Museveni has dismissed the reports that Wine had suffered serous injuries as "fake news".