Between 4:45 and 5:30 AM, Tuesday morning, heard a loud high pitched sound that would last for 10 minutes, stop and start again. Thought it was my AC at first but it was coming from the street (Mercer Street). Went on for about 45 minutes. Sounded like an alarm possibly. We have a history of Library alarm going off in the middle of the night but I don't think that was it.

Anybody else hear it? Not looking forward to a repeat performance tonight!