It was the third near-fatal or fatal collision on the highway in recent weeks, extending to nine a string of traffic crashes on Maui since May 5 that have resulted in deaths or life-threatening injuries.

While noting that the three recent crashes on Piilani Highway occurred on different stretches of the road and under different circumstances, police traffic commander Lt. Bobby Hill told The Maui News that police plan to crack down on traffic violations, starting on Piilani Highway.

"We do plan on doing more speeding and aggressive driving enforcement," Hill said. "We'll probably start targeting Kihei and Piilani Highway, and then move toward other hot spots."

The collision Tuesday was reported at 7:44 a.m. in Makena-bound lanes of the highway approaching Kilohana Drive.

A 1999 white GMC pickup truck was in the outer right-turn-only lane when it slowed down to move into the inside lane that continued straight toward Makena, said police traffic investigator Dukie Racadio. He said the truck was rear-ended by a Harley Davidson motorcycle that had been traveling behind the truck.

The 46-year-old Kihei man operating the motorcycle and the woman who was his passenger were thrown from the motorcycle in the crash, landing on the roadway, Racadio said.

Both were taken by ambulance to Maui Memorial Medical Center, where the man was treated for minor injuries, while the woman was hospitalized in the intensive-care unit with life-threatening injuries, Racadio said.

He said neither motorcycle rider was wearing a helmet.

The motorcycle slid off the roadway after the impact, landing on the right shoulder, said acting traffic Sgt. Duke Pua.

He was among traffic investigators who worked to map the collision scene that included shattered glass on the roadway from the motorcycle and right rear brake light of the GMC truck.

None of the three occupants of the truck, which was driven by an 18-year-old Folsom, Calif., man, was injured, police said. He was wearing a seat belt, as were his passengers – a 17-year-old boy also from Folsom and a 10-year-old Haiku boy, police said.

Haiku resident Jeffrey Plauche, whose young son was one of the passengers in the truck driven by Plauche's nephew, said he had been driving with his wife in another vehicle ahead of the truck as the group headed to Makena to go kayaking.

Through his rear-view mirror, Plauche said he kept an eye on the truck and saw its blinker on to change lanes.

"Next thing, I heard a boom," Plauche said. "Then I saw the people on the ground behind him.

"They slammed into the right rear."

He said the crashed motorcycle appeared to be traveling with another motorcycle that wasn't involved in the collision.

Plauche's wife, a nurse, was the first to reach and tend to the injured woman and man.

Plauche said his nephew and his best friend had just graduated from high school in Folsom and were about to end their vacation on Maui, returning home today.

"I think their holiday is done," Plauche said. "Their holiday is overshadowed by the tragedy. I hope the woman makes it."

Plauche was able to drive the truck away from the scene, while the motorcycle was towed off.

While traffic officers investigated, the police Highway Incident Traffic, or HIT team, set up an electronic sign warning drivers to slow down as they detoured around the Makena-bound lanes of the crash site between Keonekai Road and Kilohana Drive.

Makena-bound traffic was diverted into the inner Maalaea-bound lane, while the outer lane and bicycle lane were used for Maalaea-bound motorists. Makena-bound lanes were reopened just before noon.

Plauche said his nephew was driving slower than the speed limit in the congested area.

That appeared to be confirmed by preliminary investigation at the scene, Hill said.

"It appears to be almost like a low-speed type of crash," Hill said. "It looks like he had control of the motorcycle. It's just that he wasn't able to stop it in time."

Hill noted that the circumstances of the crash Tuesday differed from two other recent crashes on the highway.

A 68-year-old Oklahoma City man was killed in a June 10 collision when the car he was driving was hit by a truck that crossed the centerline on Piilani Highway near Alanui Ke Alii Road. Police are investigating suspected alcohol use by the truck driver in that crash.

Two weeks earlier, on May 27, a 49-year-old Kihei man was critically injured when his Wailea-bound car was struck by a northbound car that had crossed the centerline on Piilani Highway. The impact pushed the man's car into the oncoming lane, where it collided with another northbound car near Ohukai Road, police said. The man died June 8 at the Queen's Medical Center on Oahu, where he was flown after the crash.

Except for reckless driving and speeding in some instances, Hill said drivers and passengers in the last couple of crashes appeared to be taking precautions by using seat belts. He urged people to be careful on the road.

"We have to drive defensively and watch out for other people – that's the only thing we can beg people to do," Hill said. "What else can you do but watch out for each other?"

Twelve people have died on Maui County roads this year, compared with nine at the same time last year. Since May 5, traffic investigators have been called to the scene of fatal or near fatal collisions at least once a week.

Hill said investigators are continuing investigations and working to complete reports in the recent crashes, which included six fatalities last month.

Among the crashes still under investigation is a June 3 collision on Honoapiilani Highway that killed 8-year-old Will Smith of San Antonio. He was a passenger in a car driven by his mother that collided with another car when its driver lost control of the vehicle, veered off the roadway, then went into oncoming traffic near Ukumehame Wayside Park, police said.

Police said a 23-year-old Lahaina woman was driving the car that went out of control and broke in two in the impact.

Hill said the investigation into that crash is estimated to take a couple of months, with reports then forwarded to the prosecutor's office, which will determine whether charges will be brought.

"Because it's a child, the public wants immediate results," Hill said. "But we're working on the other six fatalities from May, too. The investigators are using all of their skills to put together all of their cases so everyone's reports will be done correctly. We cannot do them all at once."