PORTLAND, Ore. -- A century-old, dilapidated warehouse under the Fremont Bridge has burned to the ground with boats, RVs, trucks and tools inside.

Portland fire investigators believe homeless people could have started the fire, possibly with a cooking or warming fire underneath pilings that support the building over the Willamette River.

Photos: Fire destroys warehouse under Fremont Bridge

The smoke from the fire, at 1300 North River Street, shut down the bridge for several hours. Crews called for more backup and resources with second and third alarms.

When this started Sunday night just before 10 p.m., firefighters were helping to pull as many vehicles out of the building as they could.

Mike Worley's boat was near the front and was pulled out in the nick of time.

"It was really devastating. For people who own boats, I'm sure they can all agree, boats are like a family member and to lose one... it's emotional," said Worley as he broke into tears.

This was almost a tragic deja vu for the Portland man. Worley lost his first boat in the $24-million Sundance Marina Fire on Hayden Island in February 2016. He can't believe it almost happened again.

"I just thought maybe for some reason I'm just not supposed to be a boat owner."

Rob Fitch was not as lucky.

"If my truck hadn't had a dead battery, they tried to move it but couldn't start it," he said while staring at the smoldering remnants of his storage facility for the past eight years. He said he didn't have insurance and lost his work truck with all the supplies for his staging and event business, and his antique, mahogany boat.

"Her name is Nadine, and she is definitely gone, definitely gone," Fitch said crying.

His friends have set up a GoFundMe page to help get his business back on track.

A Department of Environmental Quality assessment of the site showed that asbestos was found in the rubble after the fire. But it is unlikely to pose any significant health risks, said DEQ spokeswoman Jennifer Flynt. DEQ will work with the U.S. Coast Guard and the Environmental Protection Agency on a cleanup response.

In 2014, KGW toured this warehouse, showing the holes in the floor, the west wall that had fallen into the river, which sparked environmental concerns, and the huge metal sign outside with U, marking it unsafe. According to property records, the site is worth $1 million. But with it's unsafe status, inspectors say it's hard to keep an insurance policy on the property. It also means when firefighters get dispatched to a fire at an unsafe building, that label is marked on their computers and they will not make entry inside because of the danger of structural collapse.

No one was inside the storage warehouse when this fire happened, so firefighters took a defensive position, only fighting it from the outside.

KGW watched as investigators interviewed two transients, one with visible soot on his face, who officials said had been staying under the building's dangerous pilings by the shoreline.

So far, those transients are not in custody, only questioned. The Red Cross is helping them and two other people with a place to stay and supplies.

Crime Stoppers and Portland Fire and Rescue are asking for the public's help finding investigative leads in the case. A cash reward of up to $1,000 is available for any tip that leads to an arrest. Call 503-823-HELP (4357) or submit a tip online here.