In one example, a woman was stabbed to death by a partner who overheard her making a 111 call.
Asbestos is a workplace killer, WorkSafe said, with about 220 people dying from it each year.
Someone drilling into a gas pipe is believed to be the cause.
The road has been closed at the site of the accident.
Internal Affairs Minister Jan Tinetti has been brought in to bring both sides together to help find a way forward.
The crash took place just after 1pm on Friday.
A report said the system was so old it would be hard to get replacement parts.
Emergency services received a call about a fire and loud explosion just before 4pm.