EDMOND, Okla. (AP) — The Oklahoma Corporation Commission says its Induced Seismicity Department and the Oklahoma Geological Survey are investigating several earthquakes in the central part of the state.

At least six quakes of magnitude 3.0 or stronger have struck since Tuesday in an area about 4 miles northeast of Edmond — about 15 miles northeast of Oklahoma City.

READ MORE: 75-Year-Old Arrested For Allegedly Killing Woman In Tom Thumb Parking Lot In Richardson

The strongest was a magnitude 4.2 quake Wednesday night. It knocked out two electric substations, leaving about 1,900 customers without power for about an hour.

READ MORE: Former Richardson Mayor And Developer Husband Found Guilty Of Bribery and Tax Evasion

No injuries or significant damage are reported.

The injection of wastewater from oil and gas production into disposal wells has been linked to an uptick in earthquakes, but the commission said Thursday no disposal wells are in the area. A known fault is in the vicinity.

MORE NEWS: Collin County Says Candida Auris Fungus Responsible For 4 Deaths

(© Copyright 2017 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)