Authorities in the Mozambican port town of Mocimboa da Praia have imposed a dusk-to-dawn curfew in response to frequent militant attacks in the region.
Militants have been reported to carry out beheadings and attacks on villages and defence targets in some districts of the northern province of Cabo Delgado since October 2017.
The group is locally known as al-Shabaab, and was formed in 2015 as a religious organization. It has no known links to the Somali jihadist group that bears the same name.
The group is reported 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.
BBC news agency reports the jihadists to have so far killed more than 150 people and burned more than 600 homes.