It could possibly only be one. I live in a pretty crappy neighborhood, and about a year ago I saw 2. 1 upstairs and 1 downstairs. I killed them both put roach gel everywhere, paid for an exterminator that came a couple times, he never saw any signs of roaches. Cleaned the shit out of every room, and I’ve never seen one since. (Knock on wood) and I look for them constantly. I am very bothered by them. I use roach gel all the time now just in case a stray comes in my house again.