DENVER (CBS4) – Cleanup is underway in Civic Center Park after some people got into trash bags left over from Thursday’s 4/20 rally and threw trash all over the grass and sidewalks.

So far it’s not clear who made the big mess, but an organizer of the rally said he is taking responsibility for it.

“The park had been picked up last night. All the trash had been placed in about 74 big trash bags and I believe last night, from what I hear from Parks and Rec, we had a few people come and dump all the bags out on the park,” Santino Walter told CBS4.

Walter said trash bags from the marijuana celebration should have been cleared out sooner.

“This was my fault, this was a producer mistake. I should’ve at midnight, when I staged all the stuff, I should’ve had it set up to have all the trash bags thrown into the roll-off. So, as bad as the park looks, the one thing that I know is we have a really good cleaning crew that we work with and we have the permit for today so I imagine this will look a whole lot different at noon today.”

The 4/20 rally ran from 10 a.m. to 8 p.m. on Thursday.

Employees with Denver Parks and Recreation were on hand to help deal with the mess, and while it’s unknown who actually took part in making it, some employees from the city department told CBS4 they believe some members of the homeless population are to blame.

Miguel Lopez, another organizer of the rally, says cleanup efforts were stalled Thursday night when a man with a knife started cutting open trash bags.

Lopez said he called the police’s non-emergency line and the man was asked to leave. That’s when he allegedly threatened the contracted cleanup crew with the knife.

Lopez said Denver Police arrived but he declined to press charges and said the man ran off. Denver Police say they have no record of the call or response but did say they responded to an incident at around 2 a.m. about people throwing trash into the park.