ELKHART, Ind. (AP) _ Authorities have stepped up patrols around an Elkhart theater after police say a threatening message was left on the theater's voice mail.

Elkhart police Sgt. Chris Snyder tells WNDU-TV that the message left over the weekend at the Lerner Theatre implied a “mass murder” would happen at a Sept. 12 concert. He says the theater reported it to police Monday.

The Elkhart Truth reports police have identified a suspect but haven't released information about them. Snyder said there was no new information to share about the investigation Tuesday.

Theater general manager David Smith said in a statement that the message was “serious in nature and unsettling.'' He says the theater is now reviewing its security protocol and emergency plans.