BOSTON (AP) — The Massachusetts Senate has approved a bill that requires natural gas companies to take immediate action to seal dangerous leaks.

The bill passed unanimously on Thursday would create a classification system for leaks in natural gas pipelines. Those classified as a Grade 1 leaks — posing the most risk to people and property — would have to be fixed immediately.

Grade 2 leaks, while not considered an imminent threat, would have to be repaired within one year of detection.

Gas companies would be required to report the locations of leaks and post a schedule for repairs. The companies would also be encouraged to propose repairs to aging natural gas infrastructure.

The House passed similar legislation in February. A six-member conference committee will now be appointed to work out differences in the bills.