Border patrol agents in Douglas, Arizona, removed a catapult from the border fence, February 10, 2017. US Customs and Border Protection

US border patrol agents at the Douglas, Arizona, port of entry southeast of Tucson encountered one of Mexican smugglers' more low-tech methods for moving drugs over the border on Friday.

While on patrol east of the border crossing, US agents saw several people moving away from the border fence as they approached.

"When agents arrived at the fence they found a catapult system attached to the south side of the border fence," Customs and Border Protection said in a release. "They searched the area and located two bundles of marijuana."

CBP agents dismantled the catapult, which was seized by Mexican authorities.

It was used to launch at least two bundles of marijuana, weighing about 47 pounds, into the US. The drugs were seized by US authorities.

Despite their rarity in everyday life, catapults are not unheard of in the drug-smuggling world. Authorities on both sides of the border have encountered them on several occasions.

In early 2011, near Naco, which straddles the border west of Douglas, US national guardsmen detected a catapult being set up near the border fence.

Mexican authorities, contacted by the US, responded to the scene, seizing about 45 pounds of marijuana and a 9-foot-tall catapult on a flatbed trailer. The people caught on camera setting up the catapult fled as Mexican troops approached

Later that year, cameras on the Arizona border spotted people launching objects over the border. Mexican soldiers responded and found two catapults with what appeared to be marijuana nearby.

"We've seen some incredible things, like cartels using big catapults to simply throw drugs over the border," journalist Ioan Grillo told Business Insider in early 2016. "They just put the drugs there and, whoom! — over the border fence, and then somebody picks it up on the other side."

"They erect this fence only to go out there a few days later and discover that these guys have a catapult, and they’re flinging hundred-pound bales of marijuana over to the other side," Michael Braun, a former DEA official, told The New York Times Magazine in 2012.

Mexican authorities demonstrate the use of a drug catapult, seized near Naco, Sonora state, just across the border from Arizona. The Tucson Sentinel/YouTube

Catapults aren't the only implement used to get over the fencing and walls along the US-Mexico border.

Late last year, Mexican federal police in Sonora found a van rigged with a "cannon" they believed was used to hurl drug bundles over the frontier. Inside the van, they found "an air compressor, a gasoline motor, a tank for storing air and a metallic tube of approximately 3 meters in length (homemade bazooka)."

In December, border agents in Naco arrested two teenagers who were found with a bundle of marijuana after surveillance cameras detected drugs being launched over the border by an air cannon.

The teenagers reportedly had 34 pounds of marijuana, molded into a cylinder roughly the diameter of a 55-gallon drum, according to the Tucson Sentinel.