STURGIS, S.D. (AP) _ A quarter-million motorcyclists have converged on this small Black Hills town to enjoy races, tours and general good times.

The weeklong 50th Black Hills Motor Classic has turned the town of 7,000 on the edge of western South Dakota's Black Hills into a motorcycle mecca.

''It's great, mind blowing,'' Marguerite McNeill of Queensland, Australia, said Tuesday. ''It seems to have all ages. It doesn't matter what or who you are.''

Motorcycles are parked on the six blocks of Main Street that have been blocked off to other traffic. Bikes are parked on both sides of the street and in double rows down the middle of every block.

The visitors included lawyers, bankers, police officers, doctors and housewives.

''This is just unreal to see this many people,'' said Burt Trumbower, wearing leather and a diamond stud in his left ear, as he surveyed Main Street. Trumbower, 45, a postal inspector from St. Paul, Minn., was attending his 17th rally.

Two wedding parties zoomed up and down the streets, and another couple was observed taking vows in a nearby park with a bearded, leather-clad man officiating.

Some attending the rally belong to established groups, such as Hell's Angels, Banditos and Sons of Silence.

The rally started small in 1940, and was dedicated to tours and races. The races are still held, but over the years the parties have taken precedence.

''I bet most people don't know the races go on,'' said Bruce Hubbard, president of the Black Hills Motor Classic Board, which is part of the local Chamber of Commerce. ''They just come to ride their bikes, maybe drink a couple of beers and talk to their buddies.''

The gathering officially began Monday, but bikers began arriving last week - along with extra law enforcement offiicers. The rally runs through Sunday.

The rally's relatively mellow mood was broken Tuesday night when police shot and killed a man who'd broken into a home after pounding a knife blade about 2 feet through a door, authorities said. The man also had threatened at least one other person and caused other disturbances, said Mike Jackley, Meade County state's attorney.

Authorities would not release the man's name.

''This is a very isolated incident,'' said Jackley. ''There's no good rational explanation for it. I'd say from the reports I've seen he definitely was not acting rationally.''

For the most part, the crowd is friendly, said Harold Sykora, chairman of a task force of state agencies providing support services for the rally.

''They seem to be polite. If you bump into someone on the street, they'll say 'Excuse me' and be on their way. People come here to have a good time,'' Sykora said.