Pittsburg police have arrested the man fire officials believe started a four-alarm blaze with an illegal firework Tuesday afternoon in Antioch.

According to Contra Costa Fire Protection District Prevention Capt. Robert Marshall, 32-year-old Pittsburg resident Rajnesh Reddy was arrested on suspicion of unlawfully causing a fire with injury.

Firefighters received the call at about 4 p.m. regarding a structure fire at 2665 Pittsburg-Antioch Highway in Antioch. Marshall said the fire was already well developed by the time engines arrived.

According to Marshall, the shop where Reddy worked part-time – Blue Star Tires – had a practice of using tar dissolved with gasoline to make old tires look new again. That day, officials suspect that Reddy lit an illegal firework and tossed it in the general direction of the business, sparking the fire.

Two people were injured in the fire, but were treated at a local hospital and released.

Pittsburg police took Reddy into custody later that day. It took firefighters roughly 2½ hours to get the blaze under control, Marshall said. The Pittsburg-Antioch Highway was closed for about four hours, as Pittsburg and Antioch police officers directed traffic away from the area. The fire billowed gray smoke that could be seen from all over the city.

“There weren’t any fire hydrants close by,” Marshall said, “so it took us some time to get a water supply established.”

The building housed six businesses, four of which were heavily damaged due to the partial collapse of the structure. Many of the businesses there offered services related to cars and motorcycles. Mt. Diablo Landscape Center also lists 2665 Pittsburg-Antioch Highway as its address.

The fire struck a personal chord for Kim Benner, whose Harley-Davidson motorcycle was parked at one of the businesses that succumbed to the flames. Benner heard about the fire from her daughter and raced over to the area. She joined about a dozen onlookers, who had gathered at an industrial park to try to get a glimpse of the fire.

“I just heard that something in the tire shop exploded,” Benner said. “I’m just shocked. I’m absolutely stunned right now.”