Brentford's heavy defeat at the hands of Crewe led to manager Leroy Rosenior's resignation.
The hosts went behind on four minutes when Luke Varney smashed in a loose ball in the Brentford box.
Brentford collapsed in the second period as Ben Rix curled home into the far corner from 30 yards and Varney slammed home a low drive.
David Vaughan then completed the rout when he latched onto a poor clearance to fire into the roof of the net.
Brentford: Masters, O'Connor, Charles, Frampton, Griffiths, Brooker, Pinault, Mousinho, Tillen (Kuffour 53), Moore (Onibuje 64), Wijnhard (Tomlin 69).
Subs Not Used: Brown, Skulason.
Booked: Griffiths, Moore, Mousinho.
Crewe: Tomlinson, Otsemobor, O'Donnell, Jones, Taylor, Jack, Rix, Roberts, Vaughan, Rodgers (Lowe 78), Varney (Higdon 84).
Subs Not Used: Williams, Grant, Kempson.
Goals: Varney 5, Rix 58, Varney 63, Vaughan 67.
Ref: A D'Urso (Essex).