Citations have been issued against the company where a massive explosion killed three workers and injured three others as they tested a rocket fuel. Cal-OSHA proposes a $25,000 fine against the company operated by SpaceShipOne designer Burt Rutan.

Safety inspectors issued their report and proposed citations on Friday. A spokeswoman at Rutan's "Scaled Composites" facility in Mojave told Eyewitness News Rutan was not available to comment.

The company issued a statement from Executive Vice President Doug Shane. It reads in part, "We cooperated fully with Cal-OSHA during the investigation, and we continue to work with the agency so that the enhanced procedures already implemented promote the safest workplace conditions possible."

The accident happened in July as workers tested nitrous oxide as a rocket fuel. It was a 15-second test, considered routine. But, Cal-OSHA says the workers were not adequately trained with nitrous oxide.

"The company failed to properly train its employees and supervisors, and to have policies and procedures that protect their employees in the workplace," said OSHA spokeswoman Kate McGuire in San Francisco.

In addition to Scaled Composites, a number of other space industry projects have facilities at the Mojave Spaceport. A spokeswoman at another company tells Eyewitness News, nitrous oxide is pretty much unknown in the space industry -- and probably hasn't been used in the quantities being seen at the rocket test.

At the Mojave Spaceport, county officials told Eyewitness News they would not comment on the results of the Cal-OSHA investigation. A spokesman said they wanted to carefully look over the report.

Burt Rutan's brother -- Dick Rutan was at the Mojave Spaceport Friday afternoon. Dick Rutan told Eyewitness News he hadn't seen the report yet, and he's been waiting to get a look at it.

Dick Rutan says he wants to see if the investigation findings could affect the other space projects at Mojave in any way. Dick Rutan is not connected with "Scaled Composites."

After the accident, Burt Rutan said he didn't think nitrous oxide was dangerous. Rutan successfully put the first private manned rocket up to the edge of space in 2004 -- SpaceShipOne.

In July, workers were testing fuel for SpaceShipTwo, a larger passenger vehicle being developed for Virgin Galactic.

Friday's statement from the company also reads: "Scaled Composites regrets that this accident occurred, and we have expressed our condolences to the victims and their families and provided support during this difficult time."

Cal-OSHA says Scaled Composites must pay the $25,000 fine or appeal the citation with 15 days. But, could the company face other repercussions from the fatal accident?

"The $25,000 that was assessed actually applies only to the part we were to investigate," says OSHA'S Kate McGuire. "If you're talking about actual injuries -- that has to be looked at by, say the district attorney or some other entity. We're only concerned with the actual safety surrounding the workplace."