The source of a loud echoing bang has the Palmerston North police and fire service baffled. A "deep resounding bang" was heard at about 10pm on Thursday, near Kelvin Grove. A police spokesperson said police attended the callout but they were not able to locate its source. "It was a definitely a loud deep bang - nothing like a gun shot bang, which is quick and high pitch." Palmerston North Astronomical Society member Noel Munford said the noise could have been a sonic boom created from a fire ball. But he said if it was a fire ball, then there would have been reports of people seeing a "bright light", burning space junk, shooting across the sky. Gail Lucinsky said she heard the explosive sound from the bottom of Pahiatua Track. "It was so loud that I jumped out of my skin thinking that one of my parents had fallen heavily and hit the wall in the room behind me." She said she went outside to look for a source