Aliens escape crashed ship, kill townsfolk, sheriff & FBI guy team up to track

[sarah17]

Looking for the title of a movie I saw on TV when I was a kid in the 70's where 4 different Alien Monsters start killing townsfolk of a small town. An FBI guy shows up out of nowhere to help the local sheriff hunt down and destroy them (with all the knowledge and weapons to stop them). Turns out the creatures escaped from a crashed ship (prisoners or zoo specimens?), and the FBI guy was the only surviving guard/zoo keeper and he and the sheriff become good friends. At the end of the movie, he takes off his mask to reveal his true, monstrous face when a hunter in the woods thinks he is one of the monsters attacking people and shoots him dead.
I remember there were 4 creatures---a crab-like creature, a shapechanger and two others (one was a tall furry monster). Was a good movie but have no idea what the name was or was in it. Any help would be appreciated.
Thanks!

[akiratubo]

The Alien Factor

http://www.imdb.com/title/tt0075656/

[sarah17]

Thanks! That is exactly what it is!
You Rule!