The authorities in Mocimboa da Praia, a port town in northern Mozambique, have issued a dusk-to-dawn curfew in response to frequent militant attacks.
The militants have been carrying out beheadings and attacks on villages and defence targets in some districts of the northern province of Cabo Delgado since October 2017.
Known locally as al-Shabab, the group was formed in 2015 as a religious organisation and has no known links to the Somali jihadist group of the same name.
The group is believed to be making millions of dollars from selling timber and rubies.
The northern coast of Mozambique has become a major centre for ivory, timber, heroin and ruby smuggling in recent years.
The jihadists have so far killed more than 150 people and burned more than 600 homes.