Liberty Utilities says it’s corrected a problem this morning at its distribution plant on Emerald Street in Keene that caused elevated carbon monoxide levels for two of its customers.

The technical error occurred around 6 a.m. and was resolved within a half hour, according to spokeswoman Emily Burnett.

She said crews checked homes and businesses for heightened levels of carbon monoxide, with two buildings having “very, very slightly” elevated levels of the dangerous gas, which was corrected.

All customers were cleared by 9:15 a.m., Burnett said. No injuries were reported and the incident is considered under control, Keene officials said.

People are encouraged to call 911 if their carbon monoxide alarm goes off and to evacuate until a crew arrives.