Bicycle detail

The bike was locked to a bike rack with my helmet outside of Yerba Buena Center for the Arts. When I last saw it at about 5:55pm. When I went to retrieve it from the rack at 6:15pm, only my lock and helmet were still at the rack. I thought I must have mistakenly only locked the helmet since the lock was still locked and intact, but after standing at the rack for a few moments, a security guard inside of YBCA came out and said she saw someone doing something that looked like spinning something around for a few minutes and then leave with the bike and not the lock or helmet. She said she asked for another guard to check it out, but that it was too late. There is a camera right next to the rack that recorded the event, but a Yerba Buena Gardens worker said it could only be released by Police request.