The first tropical storm of the season has left at least 19 people dead in Guatemala and El Salvador amid flash floods and mudslides triggered by heavy rains, officials in both countries said.

Tropical Storm Agatha was downgraded to a tropical depression early Sunday, but the damage caused by heavy rains and high winds prompted the government in El Salvador to declare a state of emergency.

Civil defense chief Jorge Melendez said six people have been confirmed killed in weather-related accidents in El Salvador, and two others were missing.

In Guatemala, President Alvaro Colom said the toll there had risen to 13 dead and 24 missing in the flash floods and mudslides unleashed by Agatha. He said 74,500 people were forced from their homes by threat of further cave-ins and flooding.

Among the dead were four children in a house that was swept away in a landslide.

A dozen Austrian and American tourists were evacuated from a resort 220 kilometers (132 miles) west of Guatemala City.

Colom said classes have been suspended until next week.

Colombia and the United States offered to send aircraft to ferry aid or help with evacuations of storm-hit areas, and Colom said six US military aircraft were enroute from a base in Honduras.

Guatemala City's La Aurora International Airport, however, has been closed since Friday after being showered by volcanic ash from the eruption two days earlier of the Pacaya volcano. Two people were killed and three missing after the eruption on Wednesday.

Vulcanolgists at Guatemala's national seismological institute said activity in the volcano was within a normal range, but its director Freddy Sanchez said, "it's very possible there could be more violent explosions in the coming days."

Colom said that even though the storm had eased, authorities remained on an emergency footing, adding that there were dozens of towns and villages that were still inaccessible because of roads severed by landslides.

US forecasters downgraded Agatha to a tropical depression early Sunday, saying was dissipating as it crossed Guatemala's western highlands and remnants of the storm were moving in a northwestern direction.

"This system is expected to produce total rain accumulations of 10 to 20 inches over extreme southeastern Mexico, Guatemala and much of El Salvador with possible isolated maximum amounts of 30 inches throughout tonight," the Miami-based US National Hurricane Center said.

"These rains could cause life-threatening flash floods and mudslides," it said.

Maximum sustained winds have decreased to 30 miles (46 kilometers) per hour, the center said, adding that all tropical storm warnings have been discontinued for the region.

"Additional weakening is anticipated as Agatha moves over the high terrain," the center noted.