A serious accident, possibly a fatality,  involving a motorcyclist at about 4 p.m. Friday has closed at least two key roads in southwest Renton and affected Metro Transit bus routes.

Medics were performing CPR on the motorcycle rider.

Monster Road is closed between Southwest Seventh Street and Martin Luther King Jr. Way, according to the Renton Police Department.

Martin Luther King Way also is closed at 60th Avenue South, according to the Police Department.

Initial reports indicated the accident involving the motorcyclist and a vehicle occurred on Monster Road near Oakesdale Avenue Southwest.

Beacon Coal Mine Road is also closed.

Monster Road is a commuter bypass route often used to avoid going through downtown Renton.