The Monterey Park dance hall shooter left 11 dead and may have attacked a second ballroom location, if he was not stopped by a brave citizen.

When authorities confront complex cases like this, when an active shooter is still at large, police say job one is public safety and getting accurate information out.

According to Trooper Andrew Hacke, PA State Police Public Information Officer, "You know the typical things that we definitely want to make sure in an active shooter situation is one, we want to make sure the public is safe, we want to get the information out as readily and as quickly as we can, but once again we want to make sure it's accurate."

Erie Police used their Facebook page and the resources of local news like Erie News Now during the Erie High shooting when the young gunman was at large. "So we wanted to make sure that people knew there was an active situation," said Inspector Chris Janus. "We wanted people to stay out of the area as well, we didn't want people to accidentally stumble into harm's way."

State police were at the Erie High shooting scene as well.  Locally they use Twitter to update the community when needed.  But they say public social media chatter that's not accurate can work against them. "There was information being passed around that he was apprehended, but not apprehended -- there was information that they're in the school then they're not -- there was a lot of misinformation being passed around social media that wasn't coming from credible source," Trooper Hacke said.

Registered as a government agency, Erie Police can use a Facebook local alerts feature to push out information. "We can actually send out like a push notification that will come to individual's phones so they're aware to stay out of the area, or that we may be looking for something or to seek shelter and so forth."

More and more they are able to communicate directly with the public if there's a threat or if they need the public's help.