Two people were shot during some of the worst riots in Belfast for many years.
Police confirmed that the shots were fired by both the nationalist and loyalists during skirmishes in the Short Strand area.
Two young Protestant men were reportedly shot in the legs just after midnight.
Trouble erupted on the lower Newtownards Road area at around 9pm on Monday night with petrol bombs, bricks, bottles and other missiles thrown. Homes were also attacked by paint and missiles in Short Strand.
Police who came under attack as they tried to restore calm said they believed there was “ some degree of co-ordination," in the attacks.
"There certainly were people masked up and there were certainly people wearing surgical gloves and they were attacking those homes on that side, so there was some co-ordination from that side,” Assistant Chief Constable Alistair Finlay told the BBC.
"There was some planning round this event, it just didn't spirit itself out of the ether."
Police said it was “probably the worst violence we have seen in that area for some considerable time."
This was echoed by DUP MLA Sammy Douglas who, said in the Assembly: "This morning I feel sad and dejected after witnessing some of the most vicious rioting for many years that I have seen.
"Some of this rioting is the worst it's been since 1969. For me it's a sad old reminder of how fragile peace is".
Police initially blamed the Ulster Volunteer Force for kickstarting the violence but said both sides were responsible for the gun shots.
The interface where the Loyalist Newtownards Road meets the Catholic Short Strand has long been a flashpoint for sectarian violence and was the scene of a major gun battle between the two sides in 1970.
British Soldier came under attack from nationalist youths there in 2002 (see picture)
There are fears that the recent violence could derail the peace process forged with the Good Friday Agreement in 1998.