Homes and businesses in part of San Francisco's Mission District were evacuated Wednesday morning because of a gas leak, but the evacuation order was lifted after the three damaged lines were pinched off, a PG&E spokesperson said.

The leak was reported at 10:39 a.m. near 24th and Bryant streets by an off-duty firefighter, fire spokeswoman Mindy Talmadge said.

Buildings within a one-block radius of the leak were evacuated just before 11 a.m., fire officials said.

According to PG&E, a backhoe dropped a large rock on the natural-gas pipes, causing the initial problem. The damage happened where multiple pipes came together, so crews had to dig in three separate places and pinch off gas flow in each line.

The first line was sealed off at 11:44 a.m., the second about five minutes after that, while the third took until 12:35 p.m. to pinch off.

Additional repairs to the lines will take place at about 2:30 p.m., affecting the natural gas supply to 10 customers in the area during that time.

During the initial work on the damaged lines, the area is shut down to traffic, Talmadge said.

San Francisco Municipal Railway's 48-Quintara bus line was  rerouted because of the incident, Muni spokesman Paul Rose said.