By JONATHAN LEMIRE and JAKE PEARSONNEW YORK (AP) a¿¿ A gas leak triggered an earthshaking explosion that flattened two apartment buildings on Wednesday, killing at least six people and injuring more than 60. A tenant said residents had complained repeatedly in recent weeks about "unbearable" gas smells. Rescue workers began the search for victims Wednesday evening amid the broken bricks, splintered wood and mangled metal after firefighters spent most of the day dousing the flames. Heavy equipment, including back hoes and a bulldozer, arrived to clear the mountain of debris where the two five-story East Harlem buildings stood. Flood lights were put in place. Thermal imaging cameras were used to identify heat spots a¿¿ bodies or pockets of fire. Just after the explosion, nine residents were said to be missing, but as the number of dead increased the number of unaccounted for occupants dropped. The recovery was facing hardship in the form of the weather, which was expected to drop into the 20s with rain. Some parts of the debris pile were inaccessible because of a sinkhole caused by a subsurface water main break, officials said. The fiery blast, on Park Avenue at 116th Street, not far from the edge of Central Park, erupted about 9:30 a.m., around 15 minutes after a neighboring resident reported smelling gas, authorities said. The Con Edison utility said it immediately sent workers to check out the report, but they didn't arrive until it was too late. The explosion shattered windows a block away, rained debris onto elevated commuter railroad tracks close by, cast a plume of smoke over the skyline and sent people running into the streets. "It felt like an earthquake had rattled my whole building," said Waldemar Infante, a porter who was working in a basement nearby. "There were glass shards everywhere on the ground, and all the stores had their windows blown out."