Clashes have taken place in the Yemeni capital, Sanaa, involving a unit of the elite Republican Guard near the defence ministry.
Five people were killed and at least nine wounded, military officials say.
The Republican Guard is under the command of the son of Ali Abdullah Saleh, who stood down as president in February after months of protests.
The clashes come a week after President Abdrabbuh Mansour Hadi announced a reorganisation of the military.
The Republican Guard soldiers exchanged fire with forces loyal to the government in the capital, reports say.
Witnesses said they heard heavy gunfire around the defence ministry building.
Official sources said the situation in the capital was under control by Tuesday evening.
Some of the assailants were arrested by government troops and others were holding out in buildings close to the ministry, witnesses told the AFP news agency.
The changes announced by Mr Hadi meant some of the Republican Guard units would come under the control of a new Presidential Protection Force, while others would be placed under different regional commands.
The Presidential Protection Force will also include a brigade from the army's First Armoured Division led by Gen Ali Mohsen al-Ahmar, who supported opposition protests against Mr Saleh last year.
The move was widely seen as an attempt to curb the power of Saleh loyalists in the military.
Mr Hadi is currently out of the country, attending a conference in Saudi Arabia.