You you know your Tolkien?
It is believed, however, that by Melkor’s watchfulness, he was the first of the Ainur to become aware of the Elves, and many of them he captured and took to his prisons, where they were made into the first Orcs. He also spread rumors of Oromë, telling the Elves that they should fear him, and for this reason, many fled from him and were also captured by Melkor.
http://www.silmarillionwritersguild.org/reference/silmsummaries/ofthecomingoftheelves.php