SEASIDE PARK - The Seaside Park boardwalk fire is finally out, with the lingering hot spots extinguished.

Fire marshals and arson investigators are trying to determine the cause of the massive fire that destroyed many businesses along the boardwalk in Seaside Park.

Investigators with the Ocean County Office of the Prosecutor have been centered in the south end of the Seaside Park boardwalk.

"It's been like an archaeological dig in there," a fire investigator says.

Workers say the blaze started at around 2:30 p.m. yesterday at Kohr's Ice Cream and Berkeley Sweet Shop along the boardwalk. They say they first saw smoke and flames underneath the boardwalk.

Employees tell News 12 New Jersey the fire started underneath the boards where all the electrical wiring is housed.

The flames later spread to more than 30 other buildings, part of Funtown Pier and at least one nearby condo complex. Between 350 and 400 firefighters responded to the fire at its peak. 

The Route 37 bridge linking the mainland to Seaside Heights remains temporarily closed.

Crews cut two trenches in the boardwalk to stop the flames in their tracks. 

Several firefighters and nearby residents were treated for smoke inhalation, but no serious injuries have been reported. The cause of the fire remains unknown.

The fire let off a plume of smoke that could be seen for miles as it was pushed northward by afternoon winds. Residents in nearby towns reported smelling smoke and seeing embers from the fire.

All remaining hot spots from the fire have been extinguished, according to officials.