The police chief said two members of the gang that kidnapped the medical students were arrested.
Police officers engaged kidnappers in a shootout on Thursday to rescue the 20 medical students kidnapped a week earlier, an official has said.
The Inspector-General of Police, Kayode Egbetokun, said the police secured the release with the support of the office of the National Security Adviser, Nuhu Ribadu.
He said a kidnap kingpin was killed in the gun battle while two others were arrested.
"I am pleased to inform you that the kingpin of this notorious gang was neutralised during an exchange of fire with our operatives," Mr Egbetokun said in Abuja, according to the News Agency of Nigeria.
"Two other members of the gang were arrested, with their weapons recovered."
The police chief spoke while handing over the students to their Vice Chancellors in Abuja on Sunday.
PREMIUM TIMES reported the kidnap of the 20 medical students on 15 August while travelling through Benue for a medical students conference in Enugu. Twelve of them were from the University of Jos while eight were from the University of Maiduguri.
Mr Egbetokun said seven other victims were freed during the rescue operation.
He said the successful rescue of the 27 individuals was achieved without the payment of any ransom.
The wife of one of the kidnapped medical students also confirmed the release of her husband to this newspaper.
PREMIUM TIMES reported that the kidnappers of the medical students had demanded N50 million as ransom.
On Sunday, the police chief said the two arrested suspects were already providing useful information to the police.
"These individuals are currently in our custody where they are providing valuable information that will help in dismantling their criminal network and prevent future occurrences of such abductions," he said.
He said the rescue operation was painstakingly difficult and complex, requiring not only deployment of massive resources, but also physical courage, meticulous planning and coordination.
"In this regard, I must extend my heartfelt appreciation to the Office of the National Security Adviser (NSA) whose support was instrumental in this operation.
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"I must place on record the personal commitment of the NSA, Malam Nuhu Ribadu, to the success of the operation that led to the successful rescue of the victims.
"I also wish to acknowledge the invaluable contributions of other security agencies who partnered with us, as well as the local vigilantes who played a crucial role in ensuring the success of the mission," the police chief was quoted as saying by NAN.He said the successful rescue of the victims was a demonstration of what could be achieved through teamwork for a common goal.
In their remarks, the vice chancellors of the two universities commended the Nigeria police and other security agencies for successfully rescuing the students unhurt and without payment of ransom.
The Vice Chancellor of the University of Jos, Tanko Ishaya, said the university management had concluded plans to work on the trauma associated with kidnap in the lives of the students.
Kidnapping for ransom is common in parts of Benue and many other states in Nigeria. The abductions are done by different armed groups.
