SCHENECTADY — Usually, the county’s hazmat team pays for the sort of fast-paced training that it got on Friday.

City firefighters raced from one call to the next on the busiest day in the hazmat team’s history. None of the calls turned out to be serious, but they gave the team a good workout on what was supposed to be just another day of fires and medical calls, Deputy Fire Chief Scott Doherty said.

“It really just reinforces all their training,” he said.

From that point of view, they got a good cross-section of events: they handled an evacuation, a bomb-like device, and a natural gas leak.

The busy shift began with a call from the Rotterdam Industrial Park just before 9 a.m.

“Workers had struck and ruptured a four-inch natural gas line,” Doherty said.

The Friday shift hazmat members had only just mustered at the fire department. They took monitors to the park and tracked the volatile gas for an hour to make sure it did not collect in any buildings while National Grid repaired the line.

Three hours later, they were called to inspect a bottle of liquid that had been duct-taped to a concrete pole at Mohawk Commons in Niskayuna. Duct tape was also used to create a swastika nearby. Town police deemed the event suspicious, blocked off traffic to the area at the rear of the shopping center and called in the experts.

“What we’re most worried about is whether it was a dangerous chemical or an explosive,” Doherty said.

The state police bomb squad eventually removed the bottle and determined that the liquid couldn’t hurt anyone. Town police are now investigating to determine who set up the hoax.

Just as the hazmat team was leaving Niskayuna, another call came in, this time for an office building in the city. Dozens of employees at 600 Franklin St. were reporting a sudden onslaught of headaches and nausea.

That turned out to be the most serious call of the day.

“A Mohawk Opportunities office worker set off bug bombs for some kind of infestation,” Doherty said. “We had to evacuate and close the building.”

The closure shut down an optician, an attorney and several other offices, including Mohawk Opportunities. About 30 workers were evacuated while the hazmat team methodically ventilated the building, section by section. It took nearly two hours to clear out the toxic fumes.

“The lesson is to read labels. The label would have guided them to use about three times less,” Doherty said, adding that bug bombs are a legal toxic material but should be used at night or on weekends when few people will encounter the fumes.

By 5 p.m., when the last team members rolled into their headquarters, they were devoutly hoping for a quiet night.

“We’re a busy department but we’re usually busy with fire and medical calls,” Doherty said. “I can’t remember having three [hazmat calls] in an eight-hour day before. But it reinforced their skills — in a lot of instances you’re dealing with unknowns. You always have to be careful.”