DENVER (CBS4) – Governor John Hickenlooper vetoed a bill that would have legalized the use of medical marijuana by those with autism.

The bill was passed by both the House and Senate with strong support, but the head of the Colorado Department of Public Health and Environment does not back it.

Before Hickenlooper’s decision, parents of children with autism gathered outside the governor’s office at the state Capitol.

“We ask that the governor help our children. Our kids are dying. We can’t wait another year,” said Michelle Walker whose son has autism.

We first met Michelle and her son at their home in May. He was able to take medical marijuana for seizures. His parents say the spray that they were giving him had dramatic impact on his autism.

Families were hoping to share their stories with him. Hickenlooper met with some of the parents in a closed door meeting in his office.

Other families want the same opportunity for their children. Stanford Parks and his wife have two children with autism.

“We need medical intervention and the most proven medical intervention is written on that bill,” Parks said.

One mother brought prescription bottles to show what her child has taken. She came in hopes of legalizing marijuana for autism.

Before vetoing the bill the governor expressed concerns about it.

“He has made concerns known that he is worried about the safety of marijuana. For autism, there are studies that show cannabis is safe for children,” said Walker.

The governor revealed that he has autism and Asperger’s syndrome in his family.

“If we sign that bill, we end up without question in some way encouraging more young people to look at this for an antidote for their problems,” he said while taking questions from reporters.

“Whichever side you take, you have compelling arguments,” he added.

One of those cases involves Kolt of Pueblo West. His mother Jamie Kropp described a changed child after regularly taking marijuana with the psychoactive component THC.

Outside the Governor’s office she pleaded, “Please sign this. Don’t make us fight any more. Let us go play in the park.”

The governor’s office issued this statement Tuesday evening:

While we are very sympathetic with families advocating medical marijuana (MMJ) as a safer and more effective treatment for their children, we cannot ignore such overwhelming concerns from the medical community. In vetoing this bill, we do so on sole concern that medical efficacy on MMJ to treat ASD has yet to be fully studied by medical professionals and scientific experts entrusted to this role at the Colorado Department of Public Health and Environment (CDPHE).

Communication officials for the governor added “an executive order will be issued directing CDPHE, in coordination with the Board of Health, to evaluate the safety and efficacy of medical marijuana for the treatment of autism spectrum disorders in children.”