The deaths of four people today — two men and a woman in a high-speed crash on Likelike Highway and a male motorcyclist who collided with a bus on Farrington Highway — bring the number of traffic fatalities on Oahu this year to 17.

That compares with nine traffic fatalities during the same period last year.

Honolulu police just yesterday urged motorists to drive carefully during a safety session aimed primarily at motorcycle riders.

The session was arranged following the weekend death of a speeding motorcyclist that raised the number of motorcycle fatalities in 2009 to five.

Police said speed has been a contributing factor in the majority of Honolulu's traffic deaths this year. They believe the car that crashed this morning was traveling about 100 mph.