LONDON, April 11 (UPI) -- British police investigating a multi-million dollar jewelry heist in London's diamond district said a burglar alarm went off indicating a possible problem, but investigators did not respond.
The Metropolitan Police Service, also known as Scotland Yard, said the alarm company, Southern Monitoring Alarm Company, phoned at 12:21 a.m. April 3 to report a burglar alarm had been activated at Hatton Garden Safe Deposit Ltd.
"The call was recorded and transferred to the police's CAD (computer-aided dispatch) system," police said in a written statement. "A grade was applied to the call that meant that no police response was deemed to be required. We are now investigating why this grade was applied to the call. This investigation is being carried out locally."
Investigators said an unknown number of burglars accessed up to 70 safe deposit boxes at Hatton Garden during Easter weekend, stealing an unspecified amount of jewelry. Some have estimated the amount to be up to $300 million.