The car hit the motorbike so hard it exploded, and the pieces were on fire. So was the SUV that hit it, one witness said.

“It’s hard even now,” said Didier a-Bessala, 29, who saw the crash. “I still can’t take those images out of my head.”

The devastating accident that killed 17-year-old Sean Logan this month in Reston involved a minibike that police say is dangerous and should be kept off the roads.

The bike is in a class of two-wheel vehicles that have become more popular in recent years but continue to vex public safety officials, who say they are often misused.

A-Bessala helped kick what was left of the bike out from under the SUV and put out the flames. He helped as two nurses tried to save Logan. They took off his helmet and performed CPR. The boy never showed any sign of consciousness.

Jennifer McConnell, 34, drove up just after the crash with her twins in the back seat. Traffic was stopped around the intersection. She saw the body and the fire around it. The driver of the SUV was outside his car, screaming and crying, throwing his hands in the air. A-Bessala said another bystander offered to call the man’s wife or his daughter.

After about seven minutes, the traffic moved. McConnell pulled past the intersection to the side of the road and sobbed.

Her kids were crying, too, even though at 3 years old they were too young to know what had happened. Around her were at least 10 other cars, McConnell said, stopped by the road while the drivers cried.

Minibikes like the one Logan rode are “more or less a toy,” said Joseph Moore, an officer with the Fairfax County police. They’re illegal to drive on any public road in the state.

Known as “pit bikes,” minibikes and pocket bikes, the vehicles generally fall under what Virginia law calls “motor-driven cycles” — bikes with a low seat height (less than 24 inches) and a relatively powerful engine that come with no license plate.

“The reason that they’re specifically prohibited is the low seat height” combined with a fairly powerful motor, Moore said.

For “a person riding one, their eyes, their line of sight may not be higher than the bumper of a car.”

Because their use is restricted to private property, motor-driven cycles aren’t registered and counted like other vehicles, and there isn’t much information on crashes.

But mopeds, which must have a higher seat and less power, have become a problem on Virginia roads as residents have explored more fuel-efficient alternatives to cars, Moore said. In 2012, there were 561 crashes involving mopeds in the state, resulting in 536 injuries.

“To drive a moped, you just have to be 16 and carrying some sort of identification,” he said. “You could have someone not familiar at all with the way the roadways work . . . and there’s no stipulation that that person has to be able to ride it.”

From 2009 to 2013, an estimated 4,500 people younger than 18 were seen in emergency departments for injuries associated with minibikes, said Carl Purvis of the Consumer Product Safety Commission.

From 2003 to 2012, there were 25 fatalities associated with minibikes involving minors. Of those, 15 occurred when a minibike collided with a car or other road vehicle.

Another four were collisions between two off-road vehicles. Other accidents are only tangentially related to minibike driving; two fatalities were caused by a bike backfiring and igniting a gas can that set fire to a home.

Police said Logan attempted to make a left turn from Reston Parkway onto Wiehle Avenue when an oncoming Acura had the right of way.

The Acura struck Logan’s bike and then another car headed in the opposite direction. The crash occurred May 9; Logan died in a hospital four days later.

“That was really hard to see,” McConnell said. “I just kept thinking, ‘His poor mother.’ ”

No charges have been filed against the driver of the Acura, Fairfax police said.

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