Boulder detectives are investigating an assault early Wednesday that sent a 41-year-old man to the hospital with serious injuries.

Officers were called at about 1:25 a.m. to an apartment in the 700 block of 20th Street, and the victim was inside with three other people, Boulder police spokeswoman Sarah Huntley. She said police are still investigating how the man was hurt and who was responsible.

The victim, whose name hasn't been released, suffered serious facial injuries, which means he has broken bones or lasting disfigurement, Huntley said. The injuries are not expected to be life-threatening, Huntley said.

Police suspect someone used a weapon to hurt the victim, she said, but they're still investigating a possible motive.

No one was been arrested in connection with the assault.