Updated

A Southern California couple whose three children died when a tractor-trailer rig smashed into their minivan six months ago are expecting triplets.

Lori Coble is seven weeks pregnant with two girls and a boy, who are expected in May. The 30-year-old mother had the three embryos implanted after in vitro fertilization.

"It's kind of a two-sided coin," Chris Coble, 36, told the Orange County Register. "We feel amazed that it's happening, but at the same time we're still mourning Kyle, Emma and Katie. Nothing will ever replace them. We feel joy for what's happening, but we're crying and missing the kids."

Kyle, 5; Emma, 4; and 2-year-old Katie were killed May 4 when a tractor-trailer rig slammed into the back of the family minivan on Interstate 5 in Mission Viejo. The minivan was stopped in the slow lane of traffic. The trucker was traveling an estimated 70 mph.

Lori Coble, who was driving, and her mother were injured.

The truck driver, Jorge Miguel Romero, 37, has pleaded not guilty to three misdemeanor counts of vehicular manslaughter. He could face as many as three years in prison if convicted.