Police received a call at 2:39 a.m. from the victims, who reported that three men had broken into their home on Dudley Court.
The residents were awoken when the suspects entered their bedroom and began assaulting the man.
One of the intruders restrained the woman and she bit him, Connelly said.
The other two men assaulted the male victim with an unknown object for several minutes and then left.
The men were heard speaking a foreign language, which the victims believed may have been Arabic or a similar Middle Eastern language.
Although descriptions of the suspects are vague, investigators hope someone might notice the bite mark, believed to be severe, on one of the suspects' hands, Connelly said.
At least one of the suspects is believed to be Middle Eastern with a medium skin tone. He was clean-cut and in his 20s to early 30s with a medium build and short, dark hair, police said. Descriptions of the other men were not available.
The victims were taken to John Muir Medical Center, where they were treated and released. The man victim suffered cuts and abrasions to his head, face and hands. The woman was not seriously hurt, Connelly said.
"We're still working to determine what the motive was and why the house was targeted," Connelly said.
Nothing appears to have been taken from the home, but police believe the victims put up more of a fight than the suspects had been expecting, Connelly said.
Anyone with information about the case is asked to call the Pleasant Hill Police Department's investigations division at (925) 288-4630.