The death toll from a gas explosion that flattened two buildings in New York’s East Harlem neighbourhood has risen to seven, the city’s mayor Bill de Blasio said Thursday.Rescue workers continued to search for missing people under the debris the day after the explosion, while firefighters tried to extinguish smoldering parts of the wreckage.“It has been a painful 26 hours,” de Blasio said.The mayor said 40 people have been injured in the explosion and subsequent building collapse caused by a gas leak.Surrounding buildings have been evacuated for safety reasons; however, de Blasio said they have been inspected and no structural damage was found.The explosion happened Wednesday morning, 15 minutes after local utility provider Con Edison had been notified of a gas leak, dpa reported.A representative for the utility provider said it had received no previous reports of a possible gas leak from the building in the past three years.De Blasio said 66 people were in temporary housing at a nearly Red Cross shelter due to the accident.