LONDON, ONT. -- Officials say people in roughly 20 homes in St. Thomas had to be evacuated Thursday after a natural gas leak.

The homes are located on Locust Street between Fourth and Fifth streets.

It's not clear how the leak occurred, but shortly after 12:30 p.m., St. Thomas Fire announced the gas had been shut off and residents were free to return to their homes.

Fire crews remain at the scene.