Four killed when police fire into air, as tensions rise in English-speaking areas over perceived discrimination. International organisations are calling for an investigation in Cameroon after four people were killed during unrest in the country’s English-speaking regions.

Tensions have been brewing for the past month in Cameroon’s two anglophone regions, where people say they are being treated as second-class citizens.

What began as protests by lawyers against the use of French in courts quickly spread to schools and universities after teachers agreed to strike over the dominance of the French language.

In Bamenda, the country’s largest anglophone city, at least four people were killed last week when security forces fired live ammunition in the air and launched teargas into a market despite no evidence that there was a protest taking place.

Amnesty International described actions as “excessive and unnecessary”, and urged the Cameroonian government to find out who was responsible.

Ilaria Allegrozzi, Amnesty’s central Africa researcher, said: “Responding to incidents of violence during protests with unnecessary or excessive force threatens to further inflame an already tense situation and could put more lives at risk.”

Local journalists say they have been harassed by the authorities and that the plight of local communities has not been given coverage by state-controlled media. On Monday, Zigoto Tchaya, a reporter working for France 24, was arrested and held for a day after he interviewed Barrister Bobga, a prominent activist based in Bamenda.

Nearly 200 miles south of Bamenda in Kumba – Cameroon’s second biggest English-speaking city – schools, markets and transport systems ground to a halt last week as angry residents took to the streets.

“Southern Cameroonians do not benefit anything from the French Cameroon. We want this to end this year,” said Enow John, who had joined the protest. Fellow protester Ni Achu said the movement was “ready to die for the future of our children”.