Internet services have been shut down in Cameroon's English-speaking areas after clashes involving separatists.
Security forces opened fire on demonstrators who were calling for independence at rallies on Sunday, killing at least eight people
A BBC reporter in Bamenda says the city is now in lockdown with no cars or people on the streets.
The authorities blocked the internet for three months earlier in the year amid similar unrest.
Main opposition leader John Fru Ndi told the BBC he believed that at least 30 people had died in clashes.
At least 50 people were wounded and about 200 arrested, reports say.
President Paul Biya, 84, has condemned the violence and called for dialogue.
The divisions in the central African state date back to the post-colonial settlement.
Cameroon was colonised by Germany, then split into British and French areas after World War One and was eventually reunified in 1961.
Since then the English-speaking minority has always complained that it has faced discrimination.
Protests over the last year were prompted by the imposition of French in schools and courts in the English-speaking North-West and South-West regions.