The blast on Panama's Bridge of the Americas took place about 4pm on Monday and security camera footage captured a massive fireball rising toward the top of the bridge that connects Panama's capital with an airport and numerous suburbs to the west.
Several cars were on the bridge during the explosion but their drivers were not hurt by the flames.
Authorities said that one fuel truck worker died in the explosion.
Two firefighters were injured as they extinguished the flames.
"We have no confirmation of any other people injured," Víctor Raúl Álvarez, director of Panama's Fire Department, said.
He added that the investigation is in its early stages and that the cause of the explosion has not yet been determined.
Engineers warned the fire may have affected the integrity of the decades-old bridge, a key link between Panama City and the west of the country.
Panama's Public Works Ministry posted a video on social media on Tuesday showing engineers surveying the site for structural damage.
Meanwhile, Panama's President José Raúl Mulino took to X to warn that the closing of the bridge would "cause disruption" and said "We hope to return to normal as soon as possible".
"The Bridge of the Americas is a structure that is over 60 years old. Due to the effects of the fire, if the metal structure was subjected to excessively high temperatures, it may have sustained damage," said Edwin Lewis, an engineer at the ministry.
Specialised teams were conducting evaluations of concrete and metal components.
Officials said the bridge would remain closed until its safety can be confirmed.
