"We understand that this incident may cause concern for the local community and I would like to reassure residents that there is no risk to members of the public.
"The incident has happened inside a property and those involved are believed to have been known to each other.
"Local officers are out and about in the community to offer reassurance and aid the investigation."
More top news
Durham Police have released CCTV images of a failed robbery in Kelloe and are appealing for information.
400 bales of straw, a tractor, trailer, fertiliser spreader and a bin of grain were engulfed in flames and completely destroyed.
Last night hundreds of people turned out for the official opening of Sunderland's new Fire Station arts hub.