A children’s hospital in Ontario says it has seen an increase in injuries sustained by kids playing the wildly popular Pokemon Go game.

In the past month, at least a dozen patients have ended up in the emergency room after being injured while playing the virtual reality game, the McMaster Children’s Hospital in Hamilton, Ont., said in a news release Thursday.

Dr. Anthony Crocco, chief of pediatric emergency medicine at Hamilton Health Sciences, said that number is “likely a conservative estimate” since patients don’t always tell the doctors what they were doing when they got hurt.

The injuries sustained by Pokemon Go players weren’t serious, but included bruising and sprained ankles, the hospital said. Still, Crocco said the outcomes in some cases could have been much worse.

“We’re trying to get the message out now, before we see something serious, that kids and especially parents need to have that conversation about how and where this game can be played safely,” Crocco told CTV News Channel on Thursday.

“Our message today is not to avoid this game, but to play this game safely and in safe environments.”

Crocco said that he has witnessed kids in his own neighbourhood getting into potentially dangerous situations, such as staring at their phones while riding their bikes, or not paying attention to vehicle traffic around them.

Pokemon Go requires players to go to different locations and “catch” virtual characters that appear on their smartphones.