Reuters witnesses reported that police fired tear gas and arrested many protesters in the Nigerian cities of Abuja and Lagos on Saturday during demonstrations over the worsening security situation in Africa’s most populous country.

Anger over mass kidnappings-for-ransom and a crackdown on demonstrators in Lagos last October have put the country on edge and triggered calls for the government to do more to address insecurity.

There was a heavy police presence in Nigeria’s 2 major cities as several hundred demonstrators gathered on Democracy Day, which celebrates the country’s move to civilian rule more than 20 years ago.

The witnesses saw police firing guns into the air and tear gas into the crowds to disperse protesters who brandished placards and chanted “Buhari must go”, a reference to President Muhammadu Buhari.