Part of the Upper Newtownards Road has been closed between the Knock traffic lights and Cabin Hill Park on Sunday afternoon.
A number of homes have been evacuated, with Stormont Presbyterian Church made available for those affected.
Police area the scene and diversions are in place.
Police are currently attending a security alert at Upper Newtownards Rd in East Belfast. Part of the road is closed, diversions are in place
More top news
A man has been rescued by firefighters - after getting his head stuck inside a washing machine.
Late-running passengers who attempt to pass through security with less than 30 minutes before their flight departs will now be stopped.
A Ukrainian pilot who spent two years in prison in Russia has been sworn into national parliament after being released last week.