More than 70 people were reported killed across the region of mostly poor countries wedged between Mexico and Colombia, and at least hundreds were stranded on rooftops or cut off by floods.
In Guatemala, the death toll shot up past 50 over the course of Thursday (local time), according to President Alejandro Giammattei, who said mudslides around a couple small towns swallowed about a couple dozen homes.
"Right now, we're trying to get there on foot because there's no other way," said Giammattei, referring to flooded out roads that complicated rescue efforts.
One of the fiercest storms to hit Central America in years, Eta struck Nicaragua as a Category 4 hurricane on Tuesday with winds of 241kmh before weakening to a tropical depression as it moved inland and into neighbouring Honduras.
Families waded through flooded streets of the northern Honduran city of San Pedro Sula, while cars sat almost submerged in parts of the central Guatemalan city of San Pedro Carcha, television footage and images posted on social media showed.
Overall, eight fatalities were confirmed in Honduras, as more than 5,000 people were holed up in shelters, while 63 communities were cut off from communications, according to the government. Officials said 20 bridges there had been destroyed.
Video posted on social media showed one of the bridges, spanning the Ulua River just east of San Pedro Sula, disappearing into the waterway after a raging torrent pulled it down.
The government said about 500 people were rescued from their roofs in Honduras on Thursday as water levels continued to rise, but many others were likely still stranded.
"We will not leave the area until we rescue the last person," Honduran President Juan Orlando Hernandez told media, adding that rescue efforts led by police, soldiers and firefighters will continue overnight.
Damage and destruction had spread across most of Honduras and speedboats and helicopters would be sent to take people to safety in inaccessible areas, Hernandez said earlier in the day.
Media in Nicaragua also reported two miners had been killed in a mudslide.
'Friends alive'
Guatemala's Giammattei had already declared a state of emergency in nearly half of the country's 22 departments.
In southern Costa Rica, a landslide killed two people in a house, a Costa Rican woman and an American man, officials said. Meanwhile, five people, including three children, died in flooding in Panama's Chiriqui province, near the Costa Rica border, authorities said.
There was at least one silver lining in Honduras, where 60 fishermen who disappeared at sea on Tuesday returned after taking shelter on cays until they were rescued, said community leader Robin Morales.
Calling their survival a "miracle," Morales said a man among them presumed dead from a heart attack also made it back.
"Our friends are alive, thank God," he said.
Across swathes of Nicaragua, Honduras, Guatemala and Costa Rica, high winds and heavy rain have damaged hundreds if not thousands of homes, forcing thousands to take cover in shelters.
Eta was moving northwest over Honduras and Belize and headed toward the Caribbean, at 13kmh on Thursday, the U.S. National Hurricane Center (NHC) said. Heavy rains continued and the storm's top winds edged up to 56kmh.
It is forecast to return to sea and regain momentum as a tropical storm, possibly reaching the Cayman Islands, Cuba and southern Florida in the coming days, the NHC said.
