CPS Energy spokeswoman Christine Patmon says police were allowed back into the building around 4:30 a.m. Friday.
Patmon says the utility, shortly before 1:30 a.m. Friday, received a report from police about a strong smell of natural gas and that officers were evacuating part of the building.
Patmon told The Associated Press that a contractor working in front of police headquarters struck a 4-inch gas line. Patmon says there was no fire.
She had no reports of anyone hurt.
San Antonio police did not immediately provide further details to The Associated Press.