The owners of the Oak Cliff apartment complex destroyed in May's deadly gas explosion are suing Atmos Energy, alleging the utility company failed in several ways, including not shutting off the gas quickly enough after the leak was first reported.

Atmos Energy faces lawsuit What we know: The newly filed lawsuit claims Atmos Energy also failed to properly mark its gas lines and ignored known safety risks.

The explosion killed three people, including a child, and injured five others.