COLTON (CBS) — A Colton man, who served a paratrooper in the U.S. Army, is speaking out after a frightening fall into a six-foot-deep hole over an electrical vault on a public sidewalk.

The incident along Wildrose Avenue occurred Thursday afternoon when Charles Walker, a quadriplegic, says he was returning from the store with his 7-year-old great grandson.

Greg Mills, reporting for CBS2 and KCAL9, says the pair were a few miles from home when Walker and his wheelchair tumbled into the hole that he couldn’t see because it was covered by plywood.

“I could not imagine that the piece of plywood was concealing this huge hole,” he said.

Colton firefighters were able to hoist the 67-year-old and his chair from the hole and take him to the hospital.

“They said that I didn’t have any fractures or breaks but I’m in pain. I’m in pain,” Walker said.

Colton city officials say they are investigating the incident.

“It doesn’t make sense for any city in the world to have a hole like this, unguarded,” he added.

Mills reports that as a paratrooper, Walker made 273 jumps before one didn’t go well. In 2008, he underwent surgery to correct the spinal problem but has been in a wheelchair since.