Two boys, ages 9 and 11, in upstate New York, were trapped under a 7-foot mound of snow for more than four hours before being freed Thursday by rescue workers and relatives who dug with their hands and shovels, police said. The boys had been playing in snow that had piled up in a parking lot opposite the apartment complex where they were staying in Newburgh, about 60 miles north of New York City in Orange County. Sgt. Aaron Weaver of the Newburgh City Police Department said the boys might have become trapped when a snowplow clearing the parking lot pushed the snow on top of them. The boys and the plow were on opposite sides of a snow mound, so it is likely that the plow’s operator did not see them, the police said.