In one section of the park, a group of about 200 pro-marijuana activists were holding a rally, while in other areas of the park, several other miscellaneous protest groups were also gathering. About 400 total protestors were at the park.

The pro-pot activists are marching for the legalization of marijuana. The other groups included anti-war protestors.

The protest march neared INVESCO Field just after 3:30 p.m. and the crowd intermingled with people going to see the DNC.

The person leading the march told the protestors through a bullhorn: "This is about civil rights. It's like Martin Luther King, only for weed."

Police say they are happy the crowd is calm.

One officer working the parade said, "A calm end to a great week."

Brian Vicente, a pro-legalization attorney and director of Sensible Colorado, a non-profit organization that works for drug policy reform, addressed the crowd before the march began. He had everyone recite the refrain, "I do not consent to a search," in case they were stopped by police during the march.

He also reminded the crowd that although Denver voted to make possession of less than one ounce of marijuana legal for those 21 and older, it is still illegal to smoke marijuana in public in Denver.

9NEWS Reporter Kyle Clark, who is on the scene, described the protestors as calm, bordering on happy. People on the scene said it felt more like a picnic than a protest. Some protestors were seen chasing each other with oversized, inflatable, red-white-and-blue baseball bats.

About a dozen police officers were on scene, along with their parade lead vehicle, a golf cart with an affixed traffic sign. Just before the march began, four other vans of riot police arrived.

Police were lax at the park, even allowing people to smoke marijuana within a few feet of them.

Mason Tvert with the pro-legalization group SAFER said police have not been citing people for marijuana possession this week, as his group had requested.

The march was scheduled to be the first that will target INVESCO Field, but it was not known which route the protestors would take.

With the tightened security around the venue, it was unknown how far police would allow the protestors to go.