A small earthquake followed by an aftershock rattled a suburb west of Dallas overnight, cracking some walls and knocking down pictures, but authorities reported no serious damage and the unscathed Dallas-Fort Worth airport near the epicenter kept up normal flight operations. Emergency officials said they had no indications of any injuries from Saturday's late-night quake. The initial earthquake measuring a preliminary magnitude of 3.4 struck at 11:05 p.m. CDT on Saturday and was centered about 2 miles north of the Dallas suburb of Irving, the US Geological Survey's national earthquake monitoring center in Golden, Colo., reported. He said the smaller aftershock with an estimated 3.1 magnitude occurred four minutes later and just a few miles away in another area west of Dallas. Irving's emergency operators were flooded with more than 400 calls after the initial quake as people reported such minor damage as cracks in some walls and a ceiling, pictures knocked down and a report of a possible gas leak, according to an emergency official, Pat McMacken. City officials said they were still following up on the various reports early Sunday. The Dallas-Fort Worth International Airport continued routine operations even though the shaking was felt at the airport partly located in Irving's city limits, airport public affairs officer David Magana said. He told AP that the airport, which bustles at peak hours because of 1,800 daily departures and arrivals, was in a quiet period with very little air traffic late Saturday night. He said the shaking caught the attention of those at the airport but didn't prompt any wider alarm. I would call it surprise," Magana said by phone. He said members of the airport operations team went out afterward and inspected landing strips, buildings and other airport installations and found no damage. Others reported that lightbulbs shattered during the quake. He also said magnitude estimates of the quake and aftershock could be revised after further study because the seismological station is rather distant at about 65 miles from the epicenters of the quake and aftershock. About 1,200 reports by people who felt the quake were recorded with the Colorado earthquake monitoring center soon after it hit.