Generally in the modern day, we usually use "person" only in the singular. (If I am correct, it's like человек). We generally use "people" as the plural of "person". (like люди). However, I believe that you can, technically, use "persons" as the plural of "person". I'm not sure there is any good rule about this, but I found a web article which claims that "persons" is used more in legal or very formal writing. (It's a short article and you can find it here: http://www.dailywritingtips.com/people-versus-persons/) But using it will sound less common in most situations today.
So, technically, you could say both:
There are five people working here. (more common)
There are five persons working here. (much less common, it sounds a little bookish)
Another example where people, to my ear sounds much better is the following:
People are often unreliable these days.
"Persons are often unreliable these days" sounds very strange.
Hope this helps!