The weekend death toll from slides and flooding caused by the rains has already reached 36 and the fire department said on Sunday that as many as another 100 people may have been buried by a second slide on a major highway outside the capital.
"A wall of earth fell on a bus and around 100 local people organized themselves to dig out the victims," said fire department spokesman Sergio Vasquez. "Then another landslide came along and buried them."
Emergency workers have already recovered the bodies of 18 victims at the site but warn it could take up to two days to dig out all the corpses.
The incident follows another landslide on Saturday that buried a bus, killing 12 people. Another six were killed on Saturday in separate incidents.
Record amounts of rain have fallen in parts of Guatemala and southeastern Mexico this year. Thousands of people in the Mexican Gulf of Mexico state of Tabasco have been forced from their homes by flooding.
Water levels behind some dams in the region have risen so high that floodgates have been opened.
