Yemen's port city of Aden is under a dusk-to-dawn curfew after fighting between anti-government militiamen and government forces killed at least 22 people.
Authorities say the all-night curfew is indefinite, and that it is a "precaution to deny armed elements freedom of movement."
The gunmen fired on government forces who arrived in Aden to try to secure the port facilities. The gunbattle killed 22 fighters from the two sides before the Yemenis were able to take control of the port.
The gunmen are believed to be secessionists who joined the government in battling Houthi rebels, but they demand independence in the south.
Also in Aden Monday, gunmen shot dead a moderate Sufi cleric, Sheikh Ali Othman al-Gailani, as he left a mosque.
Sufi is a mystical form of Sunni Islam that is violently opposed by Islamic State and other extremists, but no one has claimed responsibility for Monday's shooting.