Two serious houses fires in Invercargill and Christchurch: Fire and Emergency NZ investigates

Fire crews are responding to two serious house fires this morning - one in Invercargill and the other in Christchurch.

Four people are hurt, two in moderate condition, after a fire was reported just after 6am in the Invercargill suburb of Waikiwi.

Crews are also working to determine who is responsible for a house fire in the Christchurch suburb of St Albans.

Fire crews were called to the blaze on Berwick St, just before 5am.

The fire at Berwick St, St Albans in Christchurch is currently being treated as suspicious. Photo / George Heard

Fire and Emergency Southern shift manager Mau Barbara says it is being treated as suspicious.

Crews are still at the scene dampening down hotspots.