Police Friday were investigating an overnight home invasion robbery in south Fulton County that sent several people to the hospital.

Four men and two women were inside an apartment in the 4300 block of Cascade Road when the robbery took place around 1 a.m., Fulton County police Cpl. Kay Lester said.

"Officers discovered that three to four armed perpetrators knocked on the door of the apartment," Lester said. "One of the occupants inside did open the door."

She said the intruders then came in and demanded money, and began pistol-whipping the victims.

"Two of the six occupants were able to jump out the window during the incident," Lester said. She said a gun was fired, but no one was struck.

Two men and a woman were taken to Grady Memorial Hospital for treatment of injuries that Lester said were not life-threatening.

The robbers took an undetermined amount of money, Lester said. Investigators have no suspects, she said.