KAILUA — A 13-year-old Waimānalo boy was killed and his mother arrested following a two-vehicle collision last night on Kalaniana'ole Highway in Kailua.

The crash happened about 6:35 p.m. near the entrance to the Hawai'i Youth Correctional Facility.

Lt. David Nilsen, of Honolulu Police Department's vehicular homicide section, said the boy was riding in the bed of a white Ford pickup truck being driven by his 33-year-old mother. The truck was in the right lane in the Waimānalo-bound lanes when it crossed over the left lane and attempted a U-turn, Nilsen said.

The truck collided with a red BMW driven by a 58-year-old Kailua woman, he said. The impact threw the boy out of the truck's bed and onto the road, Nilsen said.

The boy was taken to the Castle Medical Center in critical condition, but he died of his injuries about an hour later.

A 12-year-old boy who also was in the truck's bed was not ejected, but he suffered serious injuries, Nilsen said. A 32-year-old man who was in the truck's passenger seat was not injured.

Police arrested the mother of the boy on suspicion of negligent homicide because of the illegal turn, Nilsen said. Charges against the woman are pending.

A supervisor at the youth correctional facility said the woman in the BMW got out of her car to give aid to the critically injured boy despite being injured herself. Nilsen said the woman was taken to the hospital by family members for treatment of minor injuries.

State law prohibits children under 12 years old from riding in the bed of a pickup truck, so Nilsen said no law was violated last night. But the death is likely to revive attempts to ban all passengers from riding in the back of a pickup truck.

In 2006, four women were killed when the pickup truck they were riding swerved to avoid an oncoming car and struck a cement truck. The women, who were on their way to work in a tomato field, were thrown from the truck.

That crash led to the introduction of a bill in the Legislature to ban riders in the back of pickup trucks. But opponents argued that a ban would be unfair to people who live in rural areas and on the Neighbor Islands where trucks are the only mode of transportation.

The measure failed to pass the Legislature.