Southend United grabbed a vital three points and look to have now secured their Division Three future.
Two goals from Leon Constantine and headers from Drewe Broughton and Leon Cort moved them up to 13th in the table.
Three months ago they looked certainties for relegation but this victory extended their unbeaten league run to eight matches.
Southend should have taken the lead when a mis-placed header from Lee Ridley fell to Constantine but the striker shot weakly at Tom Evans.
However, Constantine was not to be denied and grabbed his 21st goal of the season in the 26th minute when he slotted the ball past Evans.
The Essex side doubled their advantage just two minutes later when Mark Gower crossed to the back-post and Broughton powered a header into the net.
Scunthorpe gained a lucky way back into the game when the Southend defence let Matt Sparrow have too much space and his shot appeared to be going wide but deflected off Cort to wrong-foot Darryl Flahavan and creep into the goal.
It completed an incredible spell of three goals in less than four minutes and that was not the end of the scoring.
Southend's Cort had an effort cleared off the line by Ridley and from the resulting corner Cort headed home for his first goal of the season.
The visitors reduced the deficit back to one goal when Terry Barwick pulled the ball back to Steve Torpey who coolly finished from 12 yards out.
But Constantine secured the victory for the home side after he finished from good work from Gower and substitute Tes Bramble.
Scunthorpe had the better of the second period but this defeat leaves them in danger of relegation to the Nationwide Conference.
They are now 17th but only six points off the drop-zone and have played at least one game more than the teams below them.