A block of Parker Avenue was evacuated this morning after work on a sewer line ruptured a natural gas pipe, though residents have since been allowed back into their homes.

At about 8:30 a.m. today , the Tracy Fire Department got a call that someone from Roto Rooter working on a sewage line at a single-family home at 1470 Parker Ave. made contact with a gas line. About 15 minutes later, 13 houses and an apartment complex on Parker between Eaton and Bessie avenues were evacuated.

Division Chief David Bramell said crews were able to confirm that natural gas had somehow found its way into the sewage system, and he was concerned that the flammable gas could have backed up into nearby homes.

People were ushered to Central School, on the corner of Eaton and Parker avenues. With classes not in session for Veterans Day, the school was available as a temporary shelter.

Tracy fire received confirmation at about 11:05 a.m. that Pacific Gas and Electric Co. crews had successfully pinched off the pipe, and at 11:15 a.m. Bramell opened Parker Avenue and allowed residents to return.

PG&E spokeswoman Jana Morris confirmed it was a half-inch plastic line that was affected, and that crews were busy assessing the damage and determining a timeline for repairs.

It appeared that only one home, 1470 Parker Ave., was affected.

• Denise Ellen Rizzo and Jon Mendelson contributed to this report.