(CNN) -- At least 24 people died late Thursday in Panama in a crash between a truck and a bus, President Ricardo Martinelli said at the scene of the accident.
News reports said at least 15 people were injured.
"I have never in my life seen anything like this," Martinelli said early Friday on CNN affiliate TVN.
"The saddest thing was hearing the cell phones ringing inside the bus as desperate family members tried to call their loved ones who were not arriving at home."
Many involved in the accident were construction workers, Martinelli said.
Police said the truck hit the bus head-on as it tried to pass a vehicle at the top of the Pacora River Bridge around 11 p.m., La Prensa newspaper said on its Web site.
Another news source, telemetro.com, said high speeds on a poorly lighted segment of road may have been responsible.
The accident occurred on the outskirts of Panama City, Panama's capital.
Rescue efforts continued into the early morning.