A mass shooting in Sweden ended with at least 10 people murdered Tuesday ... and new video has surfaced capturing the terrifying moments a witness hiding in a bathroom heard the gunman firing his weapon as he closed in.

Hashem Shams shot the footage with his phone as he sat on a toilet in the cramped restroom at a Risbergska adult education center in Oreba, a city about 100 miles west of the Swedish capital, Stockholm.

Check it out ... Shams -- a student at the school -- looks totally freaked out as he listens to the "pop, pop, pop" of Rickard Andersson's gun.

One person is heard yelling something indistinguishable outside the restroom as Andersson continues his rampage, killing nearly a dozen victims.

TV4 Media in Sweden reportedly enhanced the audio and was able to interpret what the unidentified person screamed ... "You should leave Europe."

Cops said Andersson -- whose motive is unknown — died at the scene, although it's not clear how.

Swedish Prime Minister Ulf Kristersson spoke about the tragedy in a televised speech, calling the massacre the worst mass shooting in the country's history.