The death toll in a grain elevator explosion rose to four Wednesday with the discovery of a body and the confirmation of remains of another victim. And hopes for finding two missing workers alive were dimmed by a new obstacle - 5 to 6 tons of steel girders and concrete.

Sedgwick County Coroner Corrie May said the human tissue found Tuesday was identified as one of the four workers who were still missing after Monday's blast. That and the discovery of a body Wednesday brings the total to four dead, she said.The frantic search was temporarily halted at daybreak as a crane was brought into position to remove the newly found debris, which will be a dangerous maneuver because bringing the debris out could lead to a new collapse, Sedgwick County Fire Chief Gary Curmode said.

"Now you're affecting the building construction. You have to be careful," he said.

The search for the missing men had narrowed to a 600-foot section of the tunnel underneath the elevator complex.

Two groups of weary rescue workers had been shoveling grain out of the way as they tried to advance from two access points into the tunnel, one of four underneath the complex. Like quicksand, wheat kept pouring down in front of them. Then, suddenly they were blocked by debris from one of the grain bins that line the roof of the tunnel.

No signs of life had been detected since a few "thudding noises" at 2 a.m. Tuesday.

However, rescuers had found reasons for optimism: They didn't have to use oxygen in the tunnels, renewing hopes that air pockets could be keeping the men alive, Curtis Wilson, a deputy division fire chief for Sedgwick County, said before dawn Wednesday.