Hardest hit was Guatemala, with 152 people killed, dozens injured and at least 100 people missing following the floods and mudslides that swept away ramshackle homes along hills and destroyed bridges and roads, complicating rescue efforts.
President Alvaro Colom released a photograph of a sinkhole in the capital that swallowed up an entire three-story building.
In countries on the mountainous and mostly poor isthmus linking North and South America, the poorest people often build their humble homes near rivers so they have access to water, only to have their homes endangered in the rainy season by swollen rivers and mudslides.
Tropical Storm Agatha, which dumped heavy rain on the isthmus just ahead of Tuesday's first day of the Atlantic hurricane season, left as many as 22,000 dwellings destroyed in Guatemala and 155,000 people forced from their homes, about half of whom remained in shelters, officials said.
With millions of dollars in damages and the impoverished population particularly hard hit, the United States pledged 112,500 dollars and sent a plane carrying relief supplies Tuesday; the European Union pledged 3.6 million dollars in humanitarian aid.
Giant sinkhole creates chilling sight
A US airplane carrying helicopters and supplies was due in Guatemala City from its base in Honduras with four choppers from which emergency aid can be delivered to the Guatemalan Air Force, at Colom's request.
Guatemala City's response was hampered by a separate emergency: the eruption of nearby Pacaya volcano whose ash forced the closure of the capital's Aurora international airport since last week, when two people were also killed and three went missing. That left thousands of travelers stranded.
The World Bank said it was finalizing with Guatemala an 85 million dollar loan to help it cope with the two disasters.
