Seaside Park, New Jersey (CNN) -- John Sundermann was en route to his store, Big Hearted John's, on Thursday when his son called from the shop and said, "Dad, there's a fire. There's a lot of smoke coming in."
Sundermann wasn't concerned at first about his shop in Seaside Heights. The fire was down the beach, not much of a threat.
He didn't count on a 20- to 25-mph wind carrying the flames four blocks up the boardwalk from neighboring Seaside Park, consuming a massive swath of the pathway freshly rebuilt after Superstorm Sandy struck last year.
Sandy hammered Big Hearted John's, and Sundermann had reopened his doors on July 3, just in time for Independence Day celebrations. He was looking forward to keeping the store open another weekend, he said.
Sundermann hadn't seen the damage to his store when he spoke to CNN on Friday, but he got close enough to see firefighters spraying water cannons through the side door of the store, packed with clothes and beach sundries.
"I'm sure that's all messed up. I'm just worried to see if the roof is intact. That's the new front door, the 30-foot steel door we put up in the front. That's gone. So, we'll see what's going on," he said, adding that on the bright side, "At least I'm healthy and nobody got hurt."
The boardwalk was reparable after Sandy wrecked it in October, but it took hundreds of firefighters nine hours to get the fire under control by Thursday night.
About 100 firefighters were still on the scene early Friday, handling various hot spots and mopping up, said Ocean County Fire Administrator Brian Gabriel.
There were no civilian injuries and "one, maybe two very, very minor firefighter injuries," he said.
Gov. Chris Christie said during a news conference that there are reports that two or three police officers suffered head injuries after falling off a fire vehicle.
"They've been taken to a trauma unit, and as soon as we have more information on them, we'll share that with you," he said.
Dozens of businesses were destroyed in the fire, Christie said. Officials earlier noted that other structures were damaged when winds carried embers from the ice cream shop where they believe the fire started up the boardwalk to a nearby condominium complex, pier and an arcade, city and county officials said. Those later blazes were contained.
There was a firefighter convention in Wildwood, 90 miles south, at the time, so roughly 400 firefighters from 30 towns -- many of them volunteer units -- were able to respond, said Seaside Heights Mayor Bill Akers.
Had they not been nearby, the damage could have extended beyond six blocks of boardwalk in Seaside Park and two blocks in Seaside Heights, he said, estimating that reconstruction costs will reach the millions.
"We're just so grateful for what these gentlemen do every single day, putting their lives on the line to save life and property, in other communities, not just their own," Akers said.
Upon first seeing the damage Thursday, Christie said, "I feel like I want to throw up."
He added, "After all the effort and time and resources that we've put in to help the folks in Seaside Park and Seaside Heights rebuild. To see this going on ... is just unthinkable."
The Seaside Heights boardwalk was in the public eye shortly after Superstorm Sandy blew its famous Jet Star roller coaster into the water last year. The coaster was removed from the ocean in May, shortly before the boardwalk reopened for business.
On Thursday, firefighters ripped out the boardwalk at Lincoln Avenue in time to create a fire line that saved much of Seaside Heights from the fate that imperiled neighboring Seaside Park.
They dug a 20-foot trench where the street met the boardwalk to keep the brisk winds from further spreading the flames, Christie said Thursday.
"The destruction south of Lincoln Avenue, it's complete," he said.
Town officials plan to meet with business owners and help them rebuild, said Seaside Park Town Administrator Robert Martucci. Akers added that the town will also assess the damage.
"If there's a silver lining, we just built it. We have the specs. We know what we're doing," the mayor said. "We'll get it back up."
Sundermann's son, Jake, probably summed up the sentiments of business owners affected by the fire when he said he was distraught "after walking up here after Sandy and seeing homes, buildings, everything just flooded, torn -- everything with sand. And all of a sudden, everyone rebuilds, and not even a year later, it all burns."
His father, though, said the response to Sandy gave him optimism.
"I'm not ever going to get used to it, but I've dealt with it before. I didn't have that kind of hopeless feeling I had after the storm," he said. "Now I know that things can be done and we'll get back together and get it open."
Authorities are not sure what caused the fire, but Martucci said it started at Kohr Brothers Frozen Custard shop on the FunTown Amusement Pier about 2:15 p.m. Martucci was at a meeting at town offices across the street when it began.
The fire escalated to six alarms shortly before 4 p.m. ET.
Sandy destroyed the FunTown Pier, which had been partially reopened this summer. The storm also damaged local water systems, and firefighters struggled with the supply Thursday, Christie said.
They had to tap into Barnegat Bay seawater to extinguish the flames.
CNN's Laura Ly reported from Seaside Park and Eliott C. McLaughlin wrote from Atlanta. CNN's Ben Brumfield, Don Lemon, Kristina Sgueglia, Julia Talanova, Kevin Conlon, Chris Welch, Tina Burnside and Rob Frehse contributed to this report.