Lagos, Nigeria (CNN) -- Authorities in Nigeria have recovered 15 schoolchildren who were snatched by kidnappers earlier this week, a police spokesman said Friday.
The children were rescued by police late Thursday in southeastern Nigeria's Abia state, according to Yeni Ajayi, a deputy National Police spokesman. He added that the four gunmen holding them escaped.
The gunmen boarded a school bus carrying the nursery and elementary school children from Abayi International School on Monday and took them away.
There were questions as to whether the children were foreigners because they attended the international school.
The kidnappers contacted the children's school, located near the city of Aba and demanded 20 million naira -- around $130,000.
Just after the incident, authorities said the bus driver and the school teacher who were on board were in police custody and helping security forces.
Abia state is often referred to as the "kidnapping capital" of Nigeria since abductions occur there on a weekly basis.
Schools, banks and businesses have closed in the area because of the rampant insecurity and dangers posed by kidnappers.
Nigeria's President Goodluck Jonathan has condemned what he calls "utterly callous and cruel kidnapping" and ordered the Inspector-General of Police and heads of other security agencies "to take all necessary steps to rescue the abducted children and return them safely to their parents."
But many such promises have been made in the past and insecurity in Abia has only worsened.