DENVER — A cleanup crew, emptying trash cans in downtown Denver, found several Molotov cocktails at 14th and Welton Friday morning, near the busy Colorado Convention Center.

They immediately called 911.

The dispatcher told responding officers that caller said there was gasoline in the bottles.

All police would say is that the odor of the liquid was cause for concern.

The scene right now on 14th and Welton. Police say Molotov cocktails were found in area by a clean up crew and brought to this location. pic.twitter.com/sp0dUAYPi9 — Drew Snadecki (@snadshots7) May 12, 2017

Police cordoned off the area and called in the bomb squad.

Crime scene technicians swabbed the bottles for evidence, then poured the flammable liquid into paint cans and secured the lids.

Passersby were intrigued by what was going on behind the police tape.

“You feel like your safe when you’re walking around a beautiful city like Denver,” said downtown visitor Beth Rozier, “but you realize that this stuff does happen everywhere.”

“It’s shocking to me that they found that,” said Luke Rozier. “It could pose a threat.”

The investigation has been turned over to the Denver Fire Department’s Arson unit. They’ll try to figure out who placed the gas filled bottles there and why.

One officer told Denver7 that anarchists have used Molotov cocktails as weapons in other cities, that’s why it’s important to find out who placed them at a busy intersection downtown.

Denver7 reached out to the Downtown Denver Partnership to get its reaction to the gas bombs, a spokeswoman said in incidents like this, they defer to the Police Department, or in this case, the Fire Department.