I only caught the ending of this movie. Two men go on a shooting spree, killing several people. It was on a little strip mall/gallery. After that, the two characters make a suicide pact, where they were to shoot each other's head at the same time. One of them misses, hitting a light bulb near the target's head instead. The surviving one leaves.
Late 90s/early 00's.
Almost sure it was an european flick.