DENVER (AP) — Colorado regulators started work Thursday on new rules for thousands of pipelines that crisscross oil and gas fields in the state after a fatal home explosion blamed on a gas leak.

The state Oil and Gas Conservation Commission outlined the goals for the new rules in a brief meeting with industry representatives and the public.

Some energy company officials raised questions about how much it will cost them to comply with the rules and how many kinds of pipelines the rules will cover.

The rules will apply to flow lines, which carry oil, gas and wastewater from wells to tanks and other gathering equipment.

Regulators have not yet written the rules but said they would include standards for designing, testing and permanently shutting down flow lines.

The commission staff expects to write a draft of the rules by mid-October. A public hearing is scheduled for Dec. 11 and 12, and the commission could vote on the rules after that.

The rules are in response to an April 17 explosion in Firestone that killed two people and destroyed a house.

Investigators blamed the explosion on natural gas leaking from a flow line that was thought to be out of service but was still connected to a well with the valve turned to the on position.

The house was within 200 feet (60 meters) of the gas well, and the flow line was severed about 10 feet (3 meters) from the house, officials said. Investigators said gas seeped into the home's basement.

The well and pipeline were in place several years before the house was built.