The Police Department is warning residents to be on the lookout for gaping holes in the sidewalk, thanks to widespread theft of utility covers.

Be careful while walking in San Francisco. That’s the message police issued Thursday as they try to track down who’s responsible for stealing sidewalk utility covers around the city.

Someone has been stealing utility covers across San Francisco over the past two years. The San Francisco Police Department said more than 400 of these sidewalk utility covers have been reported stolen by the San Francisco Public Utilities Commission.

San Francisco police are asking the public to report stolen or missing utility covers on sidewalks that are creating hazards for pedestrians. The San Francisco Public Utilities Commission has reported more than 400 stolen sidewalk covers in the last two years,