Ryan Hall scored twice as Southend thrashed Bradford and extended their unbeaten home run to seven games.
Barry Corr gave the Blues the lead from the penalty spot after Luke O'Brien fouled Harry Crawford.
Hall doubled the lead when his 25-yard shot deflected in off Jon Worthington, with Kane Ferdinand heading in the third from Hall's cross.
Soon after Hall got his second, taking Anthony Grant's ball and finishing from a tight angle to complete the rout.
Southend United manager, Paul Sturrock told BBC Essex:
"I'm very pleased, that's two 4-0's for us and I'm delighted we have returned to a bit of form at long last.
"Our home form has been turned around and rejuvenated and I'm glad everyone has taken on board my criticisms.
"That team out there, when they play right, have some ability."
Bradford City interim manager Peter Jackson tells BBC Radio Leeds:
"Nights like this are not easy for anybody but particularly for the manager so bitterly disappointed with the result and we're seriously now in a relegation battle.
"It's a must-win game on Tuesday because we have to get a win from somewhere.
"I had seven players missing tonight through injury so that doesn't help a squad but we should have done better here. It's a massive disappointment."