Music by Kevin MacLeod. Available under the Creative Commons Attribution 3.0 Unported license. Download link: https://incompetech.com/music/royalty-free/index.html?isrc=USUAN1100747

MacLeod's description:

Genre: Soundtrack
Length: 3:04
Instruments: Strings

Deeply troubling and somber, this piece is heavy on the bass strings, especially in the last minute. The feel is very dark and funereal, and could be used to depict the beginning of the apocalypse. 035
ISRC: US-UAN-11-00747
Dark, Somber 2010