CBC videographer Tony Smyth says more than 80 firefighters — about the number who work the entire city in any one-day shift — were at the scene at the height of the four-alarm fire.
The company was closed at the time, and there were no injuries reported, but the fire caused an estimated $1 million in damages, Hamilton Fire Services said.
Hamilton Fire Services received a call about the fire at 10:25 p.m. ET at a warehouse operation at Prema Canada, which sells materials such as solvents that are used for tire retreading, Smyth said.
The caller said wooden pallets were burning outside the building, firefighters said.
Buildings 'built probably around the 1940s'
Firefighters battled the flames from the exterior, but it spread to the interior of the complex, said Dave Christopher, a Hamilton Fire Services spokesman.
"The problem we have is it's a large series of buildings," he said. "It's about four or five buildings that are interconnected, built probably around the 1940s. The fire started at one end, and progressed through, probably almost to the end of the structure so far."
Freelance reporter David Ritchie told CBC News from the scene that the fire enveloped the complex of several connected buildings.
Scott Watson stood across the street watching crews douse what remained of the fire. Watson Engraving and Signage Inc., which he co-owns, was one of the businesses gutted by the blaze.
"Luckily, we have insurance, but as of right now, we'll have to find a new place to operate out of."
Neighbour saw flames late Tuesday night
Paul Smith lives directly across the street from Watson Engraving and Signage. He said he left his front door after 10 p.m. Tuesday night when he saw firefighters working to put out flames.
"I was like, what is that?" Smith said. "We were really astounded last night by the force of it."
He said he was asked to leave his home around 1 a.m., but was allowed to return less than two hours later.
"We were worried we were breathing in black smoke," said Smith, noting that neighbours are concerned about what chemicals burned in the fire.
However, Christopher said Prema Canada was "not storing hazardous chemicals on site."
“The Ministry of Environment were there [Tuesday night] and the inspector had no concerns," he added.
Hamilton Mayor Bob Bratina visited the site around 10 a.m. on Wednesday. He said he was impressed by the "excellent efforts of a very professional fire department." Bratina also lauded crews for working to prevent run-off from seeping into nearby waterways.
He said "we've had people from the Ministry [of Environment] examine Spencer Creek and [they've said] there's no evidence that there's anything from this fire in the natural water course."
Hamilton Fire Department district chief Bill Pittman said he expects the job will take until later Wednesday morning or the early afternoon.
Pittman said he doesn't know what caused the fire.
"Until we get closer and get some water removed, we can't determine that."
A fire marshal reached the scene at around 10:45 a.m. and is currently investigating.