"Expressing anguish & pain, the Congress president said that only barbaric & inhuman groups/individuals could carry out such acts in premises of education," the Congress said in a tweet.
"Any ideology or religion can not and should not justify such acts, Smt. Gandhi added. #Kenya," said another tweet.
According to media reports, the toll in the terrorist attack has risen to 147.
The Al-Shabaab militant group has claimed responsibility.