BOULDER, Colo. - Boulder police are investigating a reported robbery at a medical marijuana dispensary where several people were sprayed with bear repellent.

The robbery was reported shortly at about 6:50 p.m.  at the Dandelion Dispensary, 845 Walnut Street, in the downtown area, according to Boulder police spokeswoman Kim Kobel.

Witnesses said two men, dressed in black and wearing ski masks, entered the business and sprayed several people.  However, Kobel said that only person could be seen on the store surveillance camera.

"Somebody came into the dispensary and sprayed a whole can of bear mace at the girl working at the counter," said Mark Levy. "I guess she was totally covered."

Kobel said three people were treated at the scene and a fourth was taken to the hospital by ambulance,  suffering from the effects of the bear repellant.

Police were working to determine if anything was taken during the assault.  The dispensary was filled with fumes from the bear repellant and police had to use gas masks to enter the business until firefighters could ventilate the building.

Police are looking for a black Pontiac Grand Prix that was seen leaving the area shortly after the incident.

Witnesses described the two assailants as between 6 feet 1 and 6 feet 2 inches in height and medium builds.  They appeared to have been white, based on what witnesses could see through the ski masks, Kobel said.