Protesters fled as military police moved in
At least two protesters have been shot dead by Ugandan police after they tried to stop the president from visiting the site of a fire at a royal mausoleum.
The protesters booed President Yoweri Museveni and set up a barricade to stop him from reaching the tombs at Kasubi.
The fire destroyed the tombs - a Unesco heritage site built in the 19th Century for kings of the Buganda region.
Supporters of Mr Museveni and Buganda's King Ronald Mutebi have been at loggerheads since riots last year.
They fell out after the king - whose role is largely ceremonial - accused the government of blocking him from visiting a part of his kingdom.
At least 20 people died in riots linked with that incident.
And angry protesters and royal advisers have said they believe the tomb fire might have been arson.
Mr Museveni, who eventually gained access to the fire scene, promised to investigate the claims.
But he said protesters had interfered with the "scene of the crime", making it difficult to find out how the fire was caused.
King Ronald also visited the scene and called for a week's mourning.
Buganda official Medard Ssegona Lubega described the fire as the "second biggest tragedy" in the kingdom's history.
"There are many men of our fallen kings lie in this house, which is now down to ashes," he told the BBC's Network Africa.
"It is something that we have built and kept and maintained for our children and grandchildren and many generations unborn."
Buganda is the largest of Uganda's four ancient kingdoms.
They were abolished in 1966 but reinstated by Mr Museveni's government in 1993.
However, he restored them only as cultural institutions with no political power.
Supporters of King Ronald believe he should have more power and influence than Mr Museveni allows.