"It was a fight that took place in the home. I don't know what it is that sparked off this incident," police spokesman Ronny Brattstrom told Aftonbladet.
Officers were called to the home in Kristinehamn at 3:30 a.m. The adult son was taken to the hospital, but the extent of his injuries is unknown, TheLocal.se reported.
Earlier Wednesday, two prisoners broke free from a correctional facility in Fosie. The suspects, who had been convicted of robberies, likely escaped to Denmark, authorities said.
The two incidents followed a series of fights and assaults across Sweden during New Year's Eve festivities, TheLocal.se said.
In Gothenburg, a man was taken to the hospital after he was stabbed at a central train station and three men armed with knives robbed a local shop.
"During the night we had a lot of drunkenness, assaults and fights but nothing astounding or some major bodily injuries," Gothenburg police officer Susanne Arvidsson told the TT news agency.