Lab Ambush is a song from F.E.A.R. 2: Project Origin. The song is track 16 on the unofficial soundtrack and was composed by Nathan Grigg.
This tune plays when Genevieve Aristide is conducting a test on Michael Becket inside the Telesthetic Attunement chamber, only it cuts short and when Armacham Forces busts inside to try to kill everyone, including Aristide herself.