Three students killed in Nigeria after kidnapping at Greenfield University -- local official

"The armed bandits who kidnapped students of Greenfield University, have shot dead three of the abducted students," said Samuel Aruwan, Commissioner for Kaduna State Ministry of Internal Security and Home Affairs, in a statement posted on Facebook.

Aruwan said the remains of the three kidnapped students were found on Friday in Kwanan Bature village, which is near the university.

At least 20 students and three staff members of Greenfield University, a private academic institution in Kaduna, northwest Nigeria, were abducted on Tuesday night by armed men, one official told CNN on Thursday.

Kaduna State Governor Nasir El-Rufai condemned the killing of three students as "sheer wickedness, inhumanity and an outright desecration of human lives by vile entities." He went on to say the armed bandits represent the worst of humankind and must be fought at all costs.

Kidnapping for ransom has escalated in Kaduna and other parts of northern Nigeria, as criminal gangs target schools that are perceived to be vulnerable. Authorities in Kaduna are, however, opposed to ransom payments. El-Rufai has previously said his administration has a policy against negotiating with kidnappers.

CNN's Samantha Tapfumaneyi in London contributed to this report.