A series of massacres were committed against Igbo people and other people of southern Nigerian origin living in northern Nigeria starting in May 1966 and reaching a peak after 29 September 1966. Between 8,000 and 30,000 Igbos and easterners have been estimated to have been killed. A further 1 million Igbos fled the Northern Region into the East. In response to the killings some northerners were massacred in Port Harcourt and other eastern cities. These events led to the secession of the eastern Nigerian region and the declaration of the Republic of Biafra, which ultimately led to the Nigeria-Biafra war.