Shaun Goater put the Essex club ahead with a penalty after 59 minutes at Roots Hall, with Marc Richards levelling for the Tykes two minutes later.
Huddersfield lost at Saltergate, despite launching a late second-half comeback as they trailed 3-0 at the break.
Wayne Allison, Paul Hall and Colin Larkin looked to have sealed all three points for the Spireites, as they held onto the lead going into the final 10 mintes.
Mark Hudson pulled one back for the Terriers, but Shane Nicholson's penalty extended the lead to 4-1 and meant goals from Jonathan Worthington (87) and Andy Holdsworth (90) were too late.
Barry Conlon hit a stoppage time equaliser for Rotherham in a 2-2 draw with Swansea, which stopped the Welsh side from going second.
Swansea were denied the chance to go second when Rotherham snatched a 2-2 draw with a 90th-minute equaliser from Barry Conlon.
Brentford also failed to make ground after being held to a goalless stalemate by 10-man Blackpool at Griffin Park.
Port Vale moved above the Iron thanks to a rare away win at Bournemouth - with Michael Cummins and Billy Paynter sealing a 2-1 win after Andrew Surman had put the Cherries ahead.
Bradford also moved above Scunthorpe, after a 1-0 win over Gillingham - though they had to wait until the final minute to make the breakthrough via Andrew Cooke.
Yeovil stunned Nottingham Forest - who had Gareth Taylor sent off after 38 minutes - with a 3-0 win at Huish Park, Phil Jevons hit two with Arron Davies also on the scoresheet.
Oldham won a seven-goal thriller at home to Bristol City, with the game finishing 4-3 in their favour.
Hartlepool beat MK Dons 2-1 in a match which saw Pools' Mark Tinkler and Dons substitute Aaron Wilbraham - who had been on for only 20 seconds - dismissed in the 88th minute for an off-the-ball incident.
Colchester's trip to Tranmere finished goalless, as did Walsall's match against Doncaster.