GUINSAUGON, Philippines — Rescue workers were thwarted today in a last-ditch effort to find an elementary school buried by a devastating landslide when a two-ton drill brought in by U.S. Marines couldn't be used and heavy rain forced officials to call off the day's search.

The drill is capable of digging 180 feet deep, and the school is believed to have been buried by up to 100 feet of mud and rock. But it went unused when U.S. Marines couldn't find the poles needed to brace it.

The search was then suspended because officials said rain made conditions too dangerous, with a number of holes that had been dug in the unstable mud collapsing.

Up to 300 children and teachers were thought to have been trapped in the school when a mountainside collapsed Friday after two weeks of heavy rain, burying the farming village of Guinsaugon in a 100-acre blanket of mud. 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.

The official death toll has reached 107, based on the number of bodies recovered, but officials fear it could surpass 1,000. Another four bodies were pulled out today, but none near the school site.

Despite an intense search, no one has been able to find the school, uncertain if it was still on its foundation or was swept away by the wall of earth, boulders and trees.

A Philippine mining engineer, Melchor Taclobao, said searchers on Tuesday had abandoned the spot where they were initially digging after hitting ground about 65 feet down. No structure was found, he said, so they started digging at another spot about 100 yards away.

Rescue workers used thick blue rope to mark off a large area they believed to be where the school was located. The site was determined using a satellite map, a topographical map and layout of property boundaries.

Philippine soldiers began digging with shovels after daybreak, while Taiwanese emergency teams set up sensors, hoping to detect sounds of survivors below the surface.