Police said investigators determined which building the screams had come from and when they went inside to investigate, they discovered the Wavertree Garden Suburb Institute Drama Group cleaning up after ending a four-day run of the musical about a serial killer, the Daily Mail reported Friday.

"The phone call was made in good faith and we would always treat calls of this nature seriously," a Merseyside Police spokeswoman said.

Another police source said: "(The tip) was taken extremely seriously because the reports seemed to suggest a serious incident was taking place.

"Thankfully no-one had been injured or worse and the actress must be praised for her impressive vocal range and the realism of her screams, which apparently caused alarm to many of the residents living close to the theater," the source said. "Officers were fully prepared for anything and I think were slightly deflated when they found the eventual cause of the commotion."