A gas leak at 12th Avenue and Olive Street was contained by Alliant Energy crews Thursday afternoon.
An unmarked gas line was hit when Alliant crews were digging a line for a new utility pole, said Alliant spokesperson Ryan Stensland.
One customer was impacted as a result of the leak, however several customers phoned in concerns about the odor, he said.
Alliant notified the Marshalltown Police Department, which responded to help make neighbors aware of the situation.
Stensland said location services are always run to identify lines underground, however an oversight resulted in the gas line not being identified.
Alliant crews continue to make repairs on utility poles that were affected by the July wind storm last year.