A boulder barreled down a steep hill and crashed into the corner of a business and ruptured a gas line in Alpine Sunday.The boulder estimated to be about 10 feet in diameter crashed through the back corner of Alpine Equipment Rentals at 2100 Alpine Boulevard Sunday around 9 a.m. No one was in the family owned rental company’s business when the incident happened. Heartland Fire Department was called at 9:22 a.m. about the ruptured gas line. Gas was turned off within 10 minutes.