Bismarck, ND -North Dakota utility regulators will begin exploring whether to penalize Xcel Energy for a Fargo natural gas explosion that demolished a Fargo duplex and injured 13 people.

Public Service Commission Chairman Kevin Cramer says the commission has appointed staffers to go over the case, and they may recommend penalties against Xcel later.

Commission staffers have finished a report on the incident, which happened last September. It says there appeared to have been a natural gas leak from part of the pipe that was serving the duplex. There was a tiny hole and a crack where the plastic pipe joined a pipeline coupler.

The report says there was gray soil around part of the pipe, which is a sign of a gas leak.

An Xcel spokeswoman says the utility will review the report. Federal advisories have previously said the pipe may be unsafe. Xcel has begun replacing more than 15 miles of gas main and almost 1,400 service lines to North Dakota homes.