Two people received gunshot wounds to the leg when a total of 11 shots were fired during the violence in the lower Newtownards Road area, which erupted at around 9pm on Monday and lasted for more than four hours.
A number of petrol bombs were also thrown during the disturbance close to the Short Stand interface, which involved around 500 loyalist and nationalist rioters, including men wearing balaclavas and camouflage.
Bricks, bottles, fireworks and smoke bombs were also thrown and homes damaged in what police called a "high-level, life-threatening, organised, serious and sustained" attack by people "hell-bent on disorder".
Police said members of the Ulster Volunteer Force were initially behind the violence, but the gun shots were fired from both sides of the community.
Chief Superintendent Alan McCrum said: "We believe at this point that members of the east Belfast UVF were involved.
"It would be a line of investigation to establish whether that was a co-ordinated and organised 'organisational' position (by the UVF central leadership).
At this point we are satisfied that at the very least members of east Belfast UVF were involved in organising the disorder.
Chief Superintendent Alan McCrum
"There were six low velocity shots fired from Short Strand and then probably five shots fired from the area of Pitt Park."
Chief Supt McCrum said two bullets hit a police landrover during the disturbance.
"There were two strike marks on one police landrover, and that clearly was an attempted murder of police officers. We believe the UVF may have well been involved in firing shots at police officers".
Asked about the shots fired from Short Strand, he said there was no indication of IRA involvement.
"There is nothing to suggest at this point that those shots were fired by Provisional members," he said.
Police fired a number of baton rounds as they tried to restore calm.
"It is probably the worst violence we have seen in that area for some considerable time," said Chief Supt McCrum.
"No-one could have anticipated the scale of the disorder last night, that hundreds of people would be on the streets and bombs and bottles would be thrown."
The First and Deputy First Ministers, who have met with the PSNI Chief Constable and the Justice Minister, have condemned those involved in the disturbances.
"It is disappointing and deeply concerning to see this level of violence return to our streets," Peter Robinson said.
"I would call on all those involved in this violence to desist immediately. The international profile of Northern Ireland has never been higher than it is now, rioting like this does our reputation real damage."
Martin McGuinness said: "A small minority of individuals are clearly determined to destabilise our communities. They will not be allowed to drag us back to the past.
"We need to ensure that tensions are not raised over the coming weeks, and I will do everything I can to assist community leaders in their efforts to bring calm to the streets."
The scenes from last night's events in east Belfast were a disgrace. I condemn those involved for the damage, fear and disruption they created in their own community.
Justice Minister David Ford
East Belfast MP Naomi Long said: "I'm devastated at the impact this has had on the people of Ballymacarrett, the Short Strand and Newtownards Road.
"They deserve better than this. I would call on those behind the attacks to bring this to an end."
Sinn Féin MLA Alex Maskey blamed the UVF for orchestrating the trouble.
"There was a UVF-related attack on the community. I'm calling on anyone with influence to bring that influence to bear and identify the problem, tackle the problem and bring that problem to an end," he told MLAs at Stormont.
Also speaking in the Assembly, DUP MLA Sammy Douglas said: "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".
Local UUP MLA Michael Copeland said the disturbances were not an isolated incident.
"The two communities share difficulties in social disadvantage and in many ways are very alike but there's a great dislike and distrust.
"There were a substantial number involved either directly or in the fringes that I would not normally have expected to see anywhere near this."
The PSNI said a police officer was injured after laser pens were used to blind officers during the trouble.
Officers are also investigating reports of an attempted hijacking of a bus and incidents of criminal damage to streetlights in the area.
The Newtownards Road has re-opened and a clear-up operation is underway.
This was the second night of trouble in the interface area of east Belfast. Police were also called in to deal with trouble involving groups of youths in the early hours of Monday.
Political leaders from both communities have appealed for calm.