Update: Luas trams are now running again in Dublin after part of the Red Line was shut down because of a gas leak in Kingswood.
Services were halted between Tallaght and the Red Cow for three and a half hours earlier.
Gas Networks Ireland, which has apologised for the inconvenience, said a gas main was accidentally damaged by a third party.
Update: Dublin Bus have now stopped accepting Luas tickets, and a replacement bus is serving the Luas stops between the Red Cow and Tallaght.
It comes as part of the Luas Red line are still shut down because of a gas leak.
Part of the Luas Red line has been shut down because of a gas leak.
Operator Transdev is warning trams may not run between the Red Cow and Tallaght until after 3pm.
Gas Networks Ireland says workers found a gas main leaking at Kingswood about 10.30 this morning
The utility says it was damaged by a third party - and its staff are working to get it fixed as fast as possible.