The first "booms" were reported to authorities on February 26, according to Berkeleyside. The noises haven't been heard every night, but streams of tweets have gradually documented their recurring nature, with people in neighboring Oakland and Emeryville also saying they've heard the sounds.
"I'd say it was around one in the morning, scared the hell out of me. I jumped out of bed," local resident Rachael Marzoline said to local KPIX 5, referring to the sound she heard on the evening of March 29.
9:51 pm, 3/31/15 - Russell & Park, bright white flash followed by the #berkeleyboom— topotowner (@topotowner) April 1, 2015
Police have received numerous calls about the booms, but when officers have ventured out into Berkeley to investigate they have been unable to pinpoint the source of the noise. Law enforcement is currently looking into the possibility that fireworks are to blame.
"At this point, it looks like it may some type of firework device. We're not positive, but we're doing some work to figure out maybe exactly where in the city these are happening at," the Berkeley Police Department's Jennifer Coats said to ABC 7 News.
Just heard a boom. Sounded like it was 40th and Market, so pretty far south to be a #BerkeleyBoom See @Berkeleyside http://t.co/fxLiLSW1eI— Brian W. Carver (@brianwc) April 1, 2015
The noises haven't been widely heard every night since February 26, but Berkeleyside states that residents have filed the most reports on March 3, 15, 17, 25 and 29. It's unclear if there's any connection regarding the days the sounds are heard. Most of the booms have reportedly taken place between 8 -10 p.m.
While police continue to look into the situation, at least one local compared the noise to a firework.
"It sounded like a firework. We actually saw kind of a flash outside of our window," resident Joshua Buswell-Charkow said to ABC 7.
Others, however, have made different comparisons. Resident Joel Bryant dismissed the idea that the sound is a gunshot but told KPIX 5 that "it sounds like an aerial bomb explosion." Some on Twitter have compared it to a pipe bomb or flash grenade.
Meanwhile, a few Twitter users have said the booms sound like a cannon, with one suggesting that officials confirm the whereabouts of the California Victory Cannon, which is set off at University of California, Berkeley football games.
When we were kids we used to put dry ice in an empty Clorox gallon jug, seal the top, wait a minute, BOOM!
I suppose that's probably some kind of serious crime now.
Have a wonderful day!