A massive fire broke out at the historic Manila Central Post Office in the Philippine capital late Sunday, with teams of fire fighters battling for more than seven hours through the night before it was finally brought under control.

The fire started around 11:45 p.m. local time and the situation was raised to the highest fire alarm level just before 6 a.m on Monday before it was brought under control about an hour later, according to the Bureau of Fire Protection.

As firefighters worked to control the flames, fire and thick smoke could be seen billowing from the windows of the neoclassical building, known for its grand entry lined with ornate columns.

Nahum B. Tarroza, director of the National Capital Region's Bureau of Fire Protection, told reporters later Monday that the internal wooden structure of the building was burned all the way from the basement to the third floor.

"It's very saddening because this is such an important part of our history," said Tarroza, adding that papers, books and mail possibly fueled the flames.

He said an investigation will be launched into the fire, and investigators haven't ruled out the possibility of an electrical fault or arson.

The post office building sits within the historic old Manila town near other tourist landmarks along the Pasig River that flows through the capital.

It was first built in 1926 and designed by Filipino architects Juan M. Arellano and Tomás Mapúa, and was severely damaged during World War II but rebuilt in 1946, preserving most of its original edifice.

It was declared an "important cultural property" in 2018, meaning the country's oldest post office was of "exceptional cultural, artistic, and historical significance to the Philippines," according to CNN affiliate CNN Philippines.

The building currently houses the Philippine Postal Corporation, the government-run postal service that handles everything from regular mail, parcels and special stamp collections.

Mark Laurente, chief of staff of the postmaster general, said that national identification cards were spared from the fire as those were stored in another city, CNN Philippines reported Monday morning.