Update, 7pm 26 June:
A 19-year-old man from Hull has been arrested on suspicion of GBH.
He has been released on police bail and inquiries are ongoing.
Update, 4.23pm 22 June:
There will continue to be a police presence in the local area tonight while we carry out further enquiries into this incident.
We believe that there may be items of clothing which have been discarded nearby, and would appeal to the public to contact us as soon as possible if they come across any items of clothing or footwear in the Boultham Park or Moorland areas.
We have a number of further lines of enquiry we are following in relation to the suspects.
The victims remain in hospital with injuries which are not believed to be life-threatening.
Officers are more than happy to speak with local residents or anyone who may be concerned, and we would like to reassure you that we believe this was an isolated incident.
We are investigating a serious assault which has left two people with injuries requiring hospital treatment.
We received several calls about disorder involving a man armed with what was reported to be a machete at an address in St Peters Avenue in the Moorland area of Lincoln just before 9.30pm last night (21 June).
Specialist officers attended the scene and found one man in his 20s with a wound to his leg and a man in his 50s who had suffered a fracture to his skull and jaw. Both received emergency care at the scene and are receiving hospital treatment. The suspects had already left the scene, and a search to locate them is now underway.
We remain on scene and in the local area today while we conduct enquiries.
We believe this is an isolated incident, and that the people involved were known to each other.
We would encourage people not to speculate about the circumstances while we carry out our enquiries.