FONTANA ( — More than 300 firearms , military-grade machine guns and over 20,000 rounds of ammunition were seized from two storage units in Fontana, police said Monday.

Steven Durant, 57, was arrested and booked on several charges of possession of illegal firearms and an explosive destructive device, Fontana police spokeswoman Martha Guzman-Hurtado said. He was on federal probation out of Arizona for the manufacturing of machine guns.

READ MORE: Davis' 28 Lead Kings To 2nd Straight Win Over Clippers

(credit: Fontana Police Department)

(credit: Fontana Police Department)

READ MORE: Family Of 18-Year-Old Garret Hayward, Killed By Suspected DUI Driver, Hold Emotional Vigil

“This is a significant arrest that takes hundreds of dangerous military-grade firearms off the street sand keeps them out of the wrong hands,” Fontana Police Chief Rod Jones said in a statement. “I am very disturbed about the number and the types of weapons seized by our officers.”

Officers responding to a call of a suspicious vehicle and person in the 13400 block of Foothill Boulevard found Durant standing near a U-Haul truck and two open storage units with several firearms, ammunition and parts in plain sight, police said. With Durant’s consent, the officers searched the storage units and found several illegal AK47’s.

MORE NEWS: In Wake Of Recent Crime Uptick, Beverly Hills Hires More Officers And Increases Patrols

With a search warrant and a more thorough search of the storage units, more than 300 firearms, military-grade machine guns, scrap parts to make illegal weapons and over 20,000 rounds of ammunition of various caliber were found.