A police officer of Englishbazar police station said two persons identified as Pandab Mandal and Prasenjit Mandal were arrested last night.
Pandab Mandal was a civic volunteer and related to Prasenjit Mandal.
Handwritten posters in Bengali were put up at the gates of co-educational Nagharia High School at Englishbazar here on Sunday demanding ransom and threatening abduction of students in case of failure to pay it.
The posters threatened to abduct ten students if the ransom of Rs two lakh was not paid but specified no date, the police said.