The Manila Central Post Office, one of the Philippine capital’s most historic buildings, was nearly destroyed by fire overnight, officials said Monday morning.

The shell of the neoclassical style structure, built in 1926, still stood. But Postmaster General Luis Carlos said the building had been completely destroyed, “from the basement to the ground floor all the way up to the fifth floor.”

“The structure is still there, but its roof has fallen down,” Carlos told reporters.

Fire officials said they were trying to determine the cause of the fire, which started in the basement Sunday night. At least one person was injured in the fire, according to investigators.

The post office, located along the Pasig River near Manila Bay, is one of the city’s most famous landmarks. Designed by two Filipino architects, Juan Arellano and Tomás Mapúa, it was partially destroyed during the Battle of Manila in World War II but restored in 1946.

The facility was the main hub for mail distribution in the capital. Mr Carlos said it was unclear how many packages and letters had been lost. Among the many items believed to have been destroyed in the fire were valuable works of art that were copied into stamps, Carlos said.

A historian, Manuel L. Quezon III, whose namesake grandfather was the Philippines’ president-in-exile when Japan occupied the country during World War II, said the fire was just the latest blow to Manila’s architectural heritage. He said many buildings that survived the war had not been properly restored.

Mr. Quezon suggested that the shell of the post office could be preserved and used to house an extension of the National Museum of the Philippines.

“The post office has been a white elephant for decades,” he said. “But its sturdy shell can be salvaged and rebuilt for the National Museum.”