A SWAT team arrested a Rancho Cucamonga man and seized a cache of replica firearms after police say he threatened a group of runners preparing for the Canyon City Marathon & Half Marathon in Azusa with what turned out to be a BB gun early Saturday.

Joseph Key Fierro, 51, was booked on suspicion of assault with a deadly weapon following the incident, which unfolded about 4:45 a.m. at Citrus and Alosta avenues, just outside of Azusa Pacific University, according to Azusa police officials and Los Angeles County booking records.

Witnesses reported a man in a truck had threatened 10 to 15 runners who were gathered in advance of the race, Officer Mike Bires said.

“The male appeared to be holding a rifle while circling the victims in his vehicle,” police said in a written statement. “He stopped and exited his vehicle, and pointed the rifle directly at the victims while making some threats,” police said in a written statement.

The man then returned to his black, raised GMC pickup truck and sped away east on Alosta Avenue, police said. The truck had a green toolbox, aluminum wheels and a passenger-side window taped up with plastic.

Several neighboring police agencies who happened to be on-hand to assist Azusa police with the marathon sprung into action and coordinated resources, Bires said. Investigators soon traced the suspect’s truck to his home in the area of Church Street and Vineyard Avenue in Rancho Cucamonga.

An Azusa police SWAT team responded to the scene and found Fierro near his truck, police said. He was taken into custody without a struggle.

Inside his truck, police found four realistic-looking guns designed to shoot plastic BBs, including two rifles and two handguns, along with accessories such as BBs, magazines and flashlights, Bires said. His motive remained unclear.

The Canyon City Marathon & Half Marathon went on without any further issues, he added.

According to county booking records, Fierro was being held in lieu of $50,000 bail pending his initial court appearance, scheduled Tuesday in the West Covina branch of Los Angeles County Superior Court.

Police are seeking any additional victims who may have had suspicious encounters with the suspect. Anyone with information is urged to contact Azusa police at 626-812-3200.