Guinsaugon, Philippines ? The U.S. Marines dug 10 feet down, then 20, but the mud began collapsing just as they tried to use their shovels to widen the little hole.

Despite growing frustration, and repeated failures, troops and volunteers pressed the search for a mud-swamped school as fears grew that time already may have run out for rescuing anyone else from a massive landslide.

And no one was sure just where to dig. “Even the local population has kind of lost their bearings,” said Lt. Jack Farley, who was leading about 40 Marines at the site. “They don’t have those terrain features around to distinguish where something really is.”

Still, the Marines promised to keep trying until all hope was gone.

Hopes for a miracle have focused on the school largely because of unconfirmed reports that survivors there sent mobile phone text messages to relatives shortly after the landslide hit Friday.

Nobody has been found alive since just hours after a mountainside collapsed in a wall of mud and boulders that swamped the farming village of Guinsaugon on Leyte island. The official death toll rose to 107 Tuesday, but authorities fear it could surpass 1,000.

High-tech gear detected some underground sounds late Monday, creating a buzz of excitement and adrenaline among troops, miners and volunteers whose hopes of finding life had all but vanished.

By Tuesday, the buzz was gone again, replaced by a grim workmanlike attitude.