Investigators are not sure how it started, but smoke was first reported coming from the roof around 5 p.m. Now, postal inspectors are tallying up the damage as nearly 1,800 post office boxes were kept inside.
Hundreds of onlookers watched as the post office went up in flames just one block away from the town square. It started around 5:30 and burned for more than an hour, stoked by a stiff wind out of the southeast.
Firefighters from as far away as Cloverdale and Santa Rosa rushed to stop the flames. The roof caved in and it is likely that much of the mail inside was damaged or destroyed.
"There's about 1,766 PO Boxes in the downtown office and all but about ten of them are rented. So, it's a pretty big blow," said USPS spokesman James Wigdel.
Wigdel says the Healdsburg post office was not a sorting center that contained mail that was to be delivered to local residents. It was only a PO Box office and drop-off center, but it was also a community meeting place for the town of about 10,000 residents.
"If it was coming from San Francisco, it would have been in the PO Boxes in Healdsburg," Wigdel said of the mail sent to those boxes.
On Monday, the postal service will set up a temporary facility at the Healdsburg Postal Annex on Foss Creek Circle at Grove Street. Claims for damaged or destroyed mail will be dealt with on an individual basis.
