Seattle ? The partygoers didn’t know Aaron Kyle Huff, and don’t know who invited him to their after-party. In the culture of raves, all-night dance parties where they say young people can feel welcomed regardless of looks or background, such questions normally aren’t important.

That trust was shattered Saturday morning, when Huff opened fire in a house full of ravers dressed like zombies in dark clothing and pale makeup, killing six of them and injuring two.

The 28-year-old man from Montana, who fired a 12-gauge pistol-grip shotgun and wore bandoliers of shotgun shells, killed himself when confronted by a police officer outside the home.

Now ravers are in shock after being struck by the apparently random act of violence.

“We’re probably the only community in society that would have welcomed somebody so easily,” said Travis Webb, an area rave promoter who attended a “zombie rave” that preceded the party where Huff opened fire.

Raves – parties that attract young people to dance to thumping, bass-laden electronic music – often are themed events where people dress up in Halloween-like outfits and paint their faces. Friday night’s rave, dubbed “Better Off Undead,” drew about 500 people, according to organizers.

While friends of the victims said they didn’t know who invited Huff, they said the invite wasn’t unusual.

“I’ve invited people to after-parties many times,” said 28-year-old Roger Platt, who attended the rave and left the after-party at the house shortly before the shooting.

Police said the gunman left the house party and returned around 7 a.m. to commit one of the biggest mass killings in city history.

Police spokesman Sean Whitcomb said Sunday that police found an assault rifle, multiple “banana clips” carrying 30 bullets each, a machete and several hundred more rounds of ammunition.

Whitcomb said the gunman was “extremely dangerous” and it was fortunate there weren’t more victims.

Four young men and two young women were killed and two people were hospitalized in serious condition, officials said.

Some who knew Huff could not believe he was a suspect in the shootings.

“This would have been so far out of character,” said Jim Pickett, the assistant manager of the apartment complex where he said Huff lived with his twin brother.

Seattle police had not released Huff’s identity Sunday, but Montana’s Flathead County sheriff’s Lt. Dave Leib said that after talking with authorities there he informed Huff’s mother Sunday afternoon that her son was dead.