A 4th of July fireworks display hosted by the city of Plano ended abruptly when the explosives ignited a sudden grassfire.

Attendees saw the intended finale explode and land on the ground, setting off a grassfire and sending viewers scrambling for cover. Motorists passing the area at Avenue K and Spring Creek Parkway captured images of the flames — posted here and here and here — spreading across Lavon Farms, where the fireworks were launched.

According to a Plano spokesperson, Plano Fire-Rescue crews responded to at least three fires in northeast Plano, believed to be sparked by fireworks. Two occurred in the area near Jupiter and Spring Creek, including one in the Oak Point Nature Preserve.

The fires were related to the city's fireworks show. No injuries were reported and it was not believed that any structures were threatened or damaged.

A release from the city says that the fire began after a 6-inch mortar exploded inside its launching tube, resulting in a chain reaction of other nearby mortars exploding as well. The show was stopped about six minutes prior to the grand finale.

The fire resulted in several acres of burned field. It took firefighters approximately one hour to contain and completely extinguish the hot spots.

The fireworks display began at 9:30 pm. An annual tradition in the city, the display was relocated for the 2020 event, to prevent the spread of COVID-19. For the first time, they were launched from Lavon Farms near Plano Event Center — a higher location than the normal launch point of Oak Point Park.

Organizers hoped that moving to a higher altitude would create a wider viewing area — allowing the display to be seen from a greater distance and thereby aid in social distancing. Residents were encouraged to view the fireworks from their homes, vehicles, or neighborhoods.

But viewers began to notice a problem just before 10 pm.

"I'm pretty sure something went wrong," said one observer on the event's Facebook page. "There was a loud boom and we could see fireworks low to the ground."

"It was the start of the finale when the fireworks got really low and then completely stopped, and the field was visibly on fire — and spreading," said another.

One viewer caught the explosions on video and posted it on YouTube, and Twitter user FxckLee captured footage of the burning fires.

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Alex Bentley contributed to this story.