Police were responding to reports of a stolen vehicle when they came under attack.
The area has been closed off and bomb disposal experts are at the scene.
Last night, violence flared in south Belfast with petrol bombs thrown and homes damaged.
Sinn Fein blamed scores of masked men, who a party representative said were wearing camouflage clothing and surgical gloves, for launching coordinated attacks on the republican Short Strand area.
Ulster Unionist Michael Copeland said he believed the violence followed attacks on Protestant-owned homes.
Belfast mayor Niall O Donnghaile, a councillor based in the Short Strand area, said a number of nationalist residents had been injured, including one man knocked unconscious when he was hit on the head with a brick.
Police were also attacked during the disturbances and advised motorists to avoid the area.
Mr O Donnghaile said: "There is no doubt that this was unprovoked and was a carefully orchestrated and planned attack on the area.
"Homes have been attacked with petrol bombs and paint bombs, bricks, golf balls. I saw what happened."
But Mr Copeland said homes on the mainly Protestant Newtownards Road had been targeted.
"I would say it was several hundred involved in very serious, almost hand-to-hand fighting," he said.
Presbyterian minister the Reverend Mervyn Gibson said houses on the Newtownards Road were being attacked from the Short Strand.
He said petrol bombs were coming from a nearby chapel's grounds and claimed two young Protestant men were shot in the legs following two bursts of gunfire.
"They were not life-threatening in my opinion but they were certainly gun shot wounds," he said.
He said homes were under sustained attack for hours.
"It was a terrible sight, I thought those days were over," he added.
Sinn Fein MLA Alex Maskey said the Ulster Volunteer Force launched a coordinated attack on the Short Strand and added that nationalist residents had stayed within their own areas.