Here Damrod and DÃriel ravaged Sirion, and were slain. Maidros and Maglor were there, but they were sick at heart. This was the third kinslaying. The folk of Sirion were taken into the people of Maidros, such as yet remained; and Elrond was taken to nurture by Maglor. (HoME 5, The Later Annals of Beleriand)
The Third and Last Kinslaying. The Havens of Sirion destroyed and Elros and Elrond sons of Earendel taken captive, but are fostered with care by Maidros (HoME 11, The Tale of Years)
Yet not all the Eldalië were willing to forsake the Hither Lands where they had long suffered and long dwelt; and some lingered many an age in the West and North, and especially in the western isles and in the Land of Leithien. And among these were Maglor, as hath been told; and with him for a while was Elrond Halfelven, who chose, as was granted to him, to be among the Elf-kindred; but Elros his brother chose to abide with Men. (HoME 5, Quenta Silmarillion)