Denver police and federal drug agents raided multiple illegal marijuana grows Tuesday morning as part of a two-year investigation.

No one has been arrested and police did not face resistance at any of the locations as officers executed search warrants, said Denver police Cmdr. Marcus Fountain. He would not say how many sites were raided or the amount of marijuana confiscated.

The grow sites were across the city, including in residential areas.

The investigation is ongoing, Fountain said.

Thus far, law enforcement has not identified any connections to gangs or cartels, he said.

Police continue to have people to interview and more locations to investigate, he said.

“It’s likely to go on for several more months,” Fountain said. “It’s that complicated.”

A Colorado resident older than 21 may grow a maximum of six marijuana plants, with no more than three being mature plants at any given time, without obtaining a license.

A Denver ordinance limits the number of plants to 12 per household, regardless of the number of adults living there.

Noelle Phillips: 303-954-1661, nphillips@denverpost.com or @Noelle_Phillips