RANCHO CUCAMONGA (CBSLA.com) — A 25-year-old bicyclist was killed Tuesday night in a hit-and-run in Rancho Cucamonga.

Michael Ray Vega was struck from behind around 6:40 p.m. while he was riding westbound on Foothill Boulevard near Ramona Avenue.

Witness Dana Carter said she found the victim bleeding in the gutter.

“He was just lying there. We were trying to help him as much as we could. We wanted to keep him from moving around a lot to risk any other injuries to his body,” she said.

Vega was wearing a helmet, but the impact was too much.

“He was hit hard enough where it could’ve possibly knocked him out of his shoes,” said Capt. Mike McCliman from the Rancho Cucamonga Fire Department.

Vega was pronounced dead at a hospital.

Sheriff’s deputies believe a male suspect was driving a white work truck with either a ladder or lumber rack on the back of the vehicle.

It’s unclear if the male driver was drunk.

“Unless the driver is intoxicated, nothing other than having a traffic accident taken is going to come out of this,” said Sgt. Greg Kreps from the San Bernardino Sheriff’s Department.

Dana Carter said she can’t understand how anyone could callously leave the victim lying in the street.

She said she hopes the driver will hear her plea.

“I just ask that you come forward, so that you can live your life at peace, as well. It would affect me thinking there was something I could’ve (done) and I didn’t do it,” said Carter.

Anyone with information on the hit-and-run is encouraged to contact police.