I saw this on Netflix. See more at Rotten Tomatoes.
I saw this on Netflix because I had just heard Leonard Martin podcast with Richard Donner, who is the director of the 4 Lethal Weapon movies, so I checked if Netflix had any movies made by him. I remember some of the later movies and I remember that it had too much violence in it and I have to say that the first movie also had too much violence and too few laughs. See more at Rotten Tomatoes.