Sameer Sheikh leaped from the third floor of the college building in suburban Jogeshwari. He suffered severe head injuries and was rushed to a private hospital in Andheri, where he was declared brought dead, they said.
The police said they have found a suicide note, but declined to divulge its content.
According to the police, the teenager was unusually quiet when he came to college this morning. He fended off repeated queries from his friends about his behaviour.
In a bid to make Sheikh happy, his friends took selfies with him, during which he said "today is my last day", police said, quoting students from the college.