"It lit up the sky and flew over us, then we heard an explosion," witness Jessica Berg told the Aftonbladet newspaper.
"It was very weird. Uncomfortably weird."
Another witness, 24-year-old Sandra, thought the light may have been due to fireworks, but began to wonder when she never heard an accompanying pop.
"Then I thought it was a comet because it looked a little like an orb. It was red with a yellow sheen that surrounded and followed it," she told the paper.
"It looked like something was falling from the sky like in a film, like Armageddon or something.
"I've never seen anything like it."
Aviation authorities were quick to rule out initial theories that a plane had crashed somewhere deep in the forests of Värmland County.
They, as well as police, suspect the mysterious night light and thunderous blast that prompted a flood of calls from concerned residents may have been caused by a meteorite.
"We don't know, but it could have been a part of the meteor shower people have been talking about," duty officer Leif Svensson of the Värmland County police told the TT news agency.
Comment: Unless it can be confirmed to have come from the particular origin point for the Geminids, then it is very unlikely that this fireball was part of a regular meteor shower.
The first calls to emergency service SOS came around 10.25pm from Forshaga, a town about 25 kilometres north of Karlstad.
More calls came from Stöllet, Ekshärad and Karlstad, and on Facebook, police in Sunne reported a rumbling reminiscent of an earthquake.
"And we've also received information that people on the west coast and even in Finland made observations," Svensson told TT.
Neither police or other authorities have plans to investigate the strange sound and light phenomena.
According to TT, Svensson chuckled when asked if uniformed officers would be sent out to comb a wide area of remote woodland in search what might be a rock from outer space before answering decisively "no".