my printer spit out a random page

My wireless printer is connected by wifi to a laptop that I rarely use and didn't bother to install webroot on and by usb to this computer that has webroot installed. Both computers are connected to internet via wifi. I just set up the wireless connection to my laptop the other day. Anyway this morning I found a very hateful racist page in my printer's output tray. It had swastikas on it and was supporting killing children and adults of non-white races in very graphic description. I was very alarmed and reported it to the local police dept but they couldn't give me any advice on the possible security breech of my computer or printer. So my question is how do I know what is hacked? There is no sign of malware on either computer that I can find but I am very limited in my knowledge of detecting threats. What do I do?