Investigators have raided about 30 homes and warehouses throughout the Denver area.

DENVER (AP) — Police and federal agents arrested more than 40 people and seized piles of pot plants and elaborate growing equipment Thursday during raids of homes and warehouses throughout the Denver area, part of a multi-state investigation into the illegal distribution of marijuana outside Colorado.

Authorities described the case as the latest example of drug traffickers seeking safe haven in the state’s flourishing marijuana industry in order to ship the drug out of state, where it can sell for more than double what it would in Colorado. Several raids in recent weeks have taken aim at out-of-state drug rings, including a sweep last month that focused on unlicensed pot grows of varying sizes.

The yearlong investigation that led to Thursday’s raids began after residents living near the grows complained about the smell of weed, a law enforcement official with knowledge of the investigation told The Associated Press. The official wasn’t authorized to comment on the ongoing investigation and did so on the condition of anonymity.

The official said the case involves people who moved to Colorado from Texas specifically to grow marijuana that would be illegally exported.

Officers searched about 30 properties during the raids, which spanned from the Denver area south to Colorado Springs. The North Metro Drug Task Force and the U.S. Drug Enforcement Administration referred questions to the state attorney general’s office, which refused to comment.

Marijuana is seen in a jar at Perennial Holistic Wellness Center medical marijuana dispensary on July 25, 2012, in Los Angeles, California.

At one home in a residential neighborhood, agents confiscated grow lights and laid them on the lawn and driveway. In an industrial spot in Denver, large pot branches were stacked up in bushy piles outside a trailer and loaded onto a National Guard vehicle, the pungent stench drawing curious onlookers.

Traffickers hide among the state’s sanctioned warehouses and farms, but also in neighborhoods where concerned neighbors sometimes tip police, authorities say.

In Pueblo, about 115 miles south of Denver, seven separate investigations this month have led to the arrests of 12 people from Florida, many of whom are originally from Cuba. The Pueblo County sheriff’s office has said all were growing the drug for shipment to more lucrative markets. Some had relocated to Colorado just weeks earlier.