An investigation is underway after an explosion blew two manhole covers from a street in Paradise Valley on Tuesday morning. Phoenix firefighters responded to reports of a small explosion in the area of 37th Street and Lincoln Drive around 9:45 a.m. When crews arrived, they found two manhole covers lying on the roadway. APS crews were also dispatched and determined the explosion happened in an underground electrical vault and that there was no active fire. As a precaution, Phoenix Fire hazardous materials teams checked the area for signs of a natural gas leak and found no problems. Fire officials say that no area homes or businesses lost power due to the incident. Eastbound Lincoln Drive was closed between 37th and 40th streets during the APS investigation into what caused the explosion.